Predicting aches and pains

I've been more-or-less out of the water since March of last year, first with tendinitis in my right shoulder, and this fall with shoulder and other aches after a couple bike crashes. I'm starting to get back into the flow of things a bit, swimming three or four times per week and remaining upright on my bike, but I find it hard (or impossible) to predict when my shoulder will act up. Saturday I wasn't expecting much, as I could feel my shoulder, but I went to lap swim anyway and had essentially no pain. By the time I was finished warming up my shoulder felt fine. I did try something different though. About four hours before swimming I took a couple ibuprofen and iced my shoulder a bit. I figured four hours would be long enough so that any pain suppression from the meds would be gone, but it would still have reduced inflammation in my shoulder. I felt fine yesterday, took the day off. I felt fine when I got up this morning. I went to practice and my shoulder bothered me a bit the entire time, enough so that I kicked nearly half the warmup and switched to zoomers for a good chunk of the main set. Now I clearly don't have the option of taking nsaids four hours before practice when it's a 6am practice (I good take some the night before), and I will admit that there likely was some residual effect on Saturday (reduced inflammation if nothing else). The fact that I felt fine on Sunday suggests to me that I didn't hurt anything Saturday. Any comment on taking nsaids well in advance of swimming to reduce inflammation? (I don't want to take them right before because they might mask pain.) I'm curious about other people's experiences. As we age (I'm 57), we are going to have more aches and pains from a lifetime of wear and tear on our bodies. How good are you at predicting whether or not a chronic joint problem you have (shoulder, knee, etc) will flare up when you swim? Skip