My tennis future?

[Ess]

In late September I was working on my serve and my right side, along my rib cage, started to get sore. I hit about 20 more practice serves and packed up and left feeling sore but not concerned. Three hours later I could barely move. There was no “pop,” and I am right handed so I assume I pulled a rib muscle. For about two weeks it was very painful, couldn’t sleep etc. After two months it was completely healed, or so I thought. I waited another month or so (hernia surgery), and on Sunday hit again for the first time since the incident. Worked for a couple hours on ground strokes, back hands, etc. and went to practice serving. The very first attempt resulted in a return of the pain. I stopped immediately, went home to ice and ibuprofen. A couple hours later it was worse than the first time it already happened (far worse than the pain of my hernia surgery recovery). My question is how do I avoid this happening again (stretching beforehand?), I waited almost three bloody months shouldn’t any pull have been healed? Will I ever be able to play competitively again? I only have a few posts on here but am always on this site. I respect a lot of the people on these boards and recognize that many of you share the same passion I have for tennis. I am gutted and have actually been very emotional over the whole thing. Tennis is my life and I am uncertain of how this will play out for me. Thanks.