Peter Parker has been half living with his Aunt May and with Tony Stark.  The two adults had a sort of unspoken shared custody over the youth.  And throughout his entire life but especially after becoming spider-man, Peter had had a few mental health issues, especially concerning anxiety.  Which of course seems to show up at the worst of times, as in now. 

Peter had been out patrolling when he saw a small group of people being armed at gunpoint. He was about to swoop in to save the day whenever he felt that oh so horrendous tightening of his airway and the first pricks at his eyes.  Karen piped up immediately as his heart rate increased,

"You appear to be displaying the beginning signs of a panic attack, Peter. Would you like me to notify Mr.Stark?"

Peter swiftly declined as he had no right to worry his billionaire mentor. Then took a few shaky breaths and kept going because the world wasn't going to wait for him. He swung in and knocked the gun out of the guys hand before webbing him to the ground. He was just webbing the second guy when he heard a shot ring out incredibly loud. His ears were buzzing but he was only worried that none of the civilians had been hit. No one was and thus forth he quickly went about taking down the third and final hooligan before swinging back to the roof tops. 

The second his feet had hit solid ground he crumbled into a sprawled sitting position.  Peter tore off his mask, closed his eyes tightly, and propped up his head with his hands. As warm tears slid from his eyes he tried to contain himself and control his breathing which at this point was quivering and raspy.  His ears were only beginning to stop buzzing when he first heard Karen again although she had repeated herself multiple times.

"Peter, you've been grazed by a bullet on your left shoulder. I advise you to get medical help immediately and to inform Mr.Stark."

Peter replied," No,no,no,no Karen I'm fine. I'm heading back home right now and will take care of it. Please don't inform Tony." To which Karen shortly answered, 

" Alright, Peter."

Peter sighed in relief and sunk his head down on his arms. His shoulder wasn't hurting too badly yet but he knew the longer that he didn't attend to it the more that the throb would become a slicing pain.  Therefore he got to back up and swung home to May's house.  

When he arrived he peeled himself out of the suit and went into the bathroom where the first aid kit was located.  He knew he was lucky because a few inches over and his arm wouldn't be able to move much for months. Peter quickly set about disinfecting the graze and wrapping it with bandage.  After that was done he clambered into his bed and drifted painfully slow into sleep.

_____________________________A WEEK LATER_______________________

Peter was working quietly and diligently in Tony's lab, at Stark Industries/Avengers Tower, upon modifications for his web shooters. Tony was working in a different corner of the lab on some variation of the Iron Man suit. They had been in the lab for maybe and hour and half whenever Tony came over and looked over the equations Peter was using. He was scanning over the work when he piped up and asked,

"This new web fluid has a much higher acceleration than the old one?"

Peter merely nodded his head as he was working on one of the most delicate bits of the product. 

Tony continued  casually with," It will definitely be of use so you don't get hit with another bullet like last week. Of course with the right technique you never would have been hit in the first place."

Tony watched Peter intently as the boy completely froze for a split moment  and his eyes widened until he realized what he had done ,continued with his work ,and saying," Agreed, the acceleration will definitely make patrols a lot quicker."

Tony replied," Not what I was implying in the slightest but it will definitely do that as well. Now look at me." Peter reluctantly set down the fine tool he was using and turned in his chair to face his mentor.  Tony studied Peter's face before saying, " What happened?" Peter hesitated before giving a brief answer," I just got distracted with only one person instead of both of them. That's all." Tony nodded and asked Peter to go to Bruce and make sure that it would heal properly.  Bruce said it was okay of course and Tony dropped the subject. That is until it reappeared again two months later.