Shoulder trouble when throwing

(M23) Recently I joined a flag football league and the season starts in 2 weeks. In preparation I’ve been practicing with the team. I’ve had a total of 4 practices thus far. I play QB for the team and I’ve noticed that the rest time for my shoulder/arm to feel good enough to throw is taking much longer than it has in the past. I played year round for multiple teams and multiple days of the week starting 3 years ago and was fine. No issues besides just being sore of course. I took 2 years off and now I’m facing issues.

My shoulder doesn’t hurt when throwing, it just feels dead. Like a wet noodle. I can generate very little power when throwing. I feel soreness in the front of my shoulder and the back but nothing really extreme. Like a 1-2 out of 10 on the pain scale. To give more context, I had a practice a month ago which was my first time really throwing a football in this type of setting in 2 years. I stretched out and felt amazing. No issues on the field. I threw a lot probably like 200 passes that day. I felt great so I decided to go again the following week 6 days later to just throw with some friends and I couldn’t throw past 10 yards. Just felt like a wet noodle for an arm when throwing. Fast forward to last Saturday and we had our second practice and again I felt great. We decided to have practice again this past Wednesday and I felt powerless when throwing once more. Then this Sunday, I thought I’d try again and it was the same thing. Maybe marginally better by like 5%. I’m guessing my arm/shoulder is obviously not used to the output that I’ve been playing at again recently. Starting in 2 weeks I will be playing a game every Sunday and I don’t want to face this issue. I’ve never been diagnosed or had an arm or shoulder injury. So my guess is to strengthen my arm and get it used to this much activity, but how can I do that. Do I keep throwing? Do shoulder exercises? Will this go away in time and can I be at the point of throwing a high volume of passes 2 times a week? At minimum once a week for my games? Just looking for general advice or ideas on where to go from here.