You may be overdoing things. Slow down, listen to your penis. Some soreness can be expected, but doesn’t necessarily happen. Now listen carefully, Pain is BAD!
If your erections are real strong it is an indication of overworking the penis. Relax ok, don’t be in a hurry here. (I know, I know, easier said than done.) It sounds like you are just trying to do to much and your body is letting you know that. And I knew what you meant by feeling sour, don’t let the guys give you to hard of a time, and yet try and chose the most appropriate word.
Try easing up on the exercises, you may be gripping to tight or exerting to much force in the jelq which will cause the “sour” feeling.