Just what I was looking for! Been listening to y'all for a few years. You guys rock!

U guys are my gift

Hi guys, looking for advice. I am 50 and started weight training about a month ago. I never considered myself old until recently. I had trained on and off in HS, college, and in my early 30s until I was almost 40 with no major injuries. The program I am using is a 5x5 with a 5 lb progression with basic lifts such as squat, deadlift, Oh press, rows, bench press and just a couple accessory moves. Last couple weeks I am experiencing several different small injury “warnings” if you will. Knee patellar tendon pain, pain in my upper lat where it meets under my shoulder, tricep tendonitis where I had to stop my OH presses abruptly due to a strain in my tricep. All these are starting to have me reset the weight MUCH lower to avoid a real injury. I feel I’m not making progress and the gym I go to doesn’t have anything smaller than 5 lb plates to add. My questions are, what can I do to avoid these tendon pains, and more importantly, what approach is best when trying to progress? I thought about doing a couple or few workouts with the same weight before progressing, but that doesn’t seem like “progression”, although I do want to prevent injury and hope my body and tendons adapt. I’m wondering if I jumped in too quickly with adding weight too fast, or maybe I should do a 3 set x 8-10 rep range that will inherently be less weight than the 5x5?.After a month my numbers are still low, but feel heavy and I don’t think that without any pain I’d still be able to progress much more without having to continually reset. My calories are around 2500-2800 with the 1g of protein per lb of body weight. I weigh 219. Gained 9 lbs since I started. This is probably a loaded question, but being 50 really hit me harder than I thought. I used to do a lot of cardio and hiit with body weight movements and no injuries. Thanks for any guidance!