MuchMoreThanMuscle saidThat is bizarre. By the way you described your symptoms it almost sounds like a nerve damage or impingement.
It could also be one of the rotators. Rotator cuff muscles are highly involved in chest pressing movements. They are also responsible for other movements too but certain rotators facilitate chest pressing movements.
I would see a specialist to determine what you are ailing from. Do not take advice from people on this site. But I will say this. Muscles that simply give out on you and collapse are usually related to some type of nerve damage.
Good luck. I hope you recover swiftly.
Hi. Yeah so what MMTM is saying is entirely possible. Bench pressing the wrong way can get you into some trouble. I had a frozen shoulder about 2 years ago that seemed to take forever to heal. Lasted about 3 months.
Tried acupuncture physio you name it but in the end the one thing that worked was a shot of cortisone. http://www.medicinenet.com/cortisone_injection/article.htm
When the freezing wears off your entire arm can feel like someone just whacked you with a sledgehammer. Depending on your physical shape age immunity it can last anywhere between a day and 2 weeks.
Mine lasted for a day and a half. Judging from your profile yours may be around the same. Cheers!