Not a doctor or PT.
I’ve dealt with many tendon issues as a long distance runner who has a history of spamming the too much too soon button. The two hardest tendon issues for me to resolve were insertional Achilles Tendinopathy (AT) and gluteal Tendinopathy.
Three pieces of advice:
1. Some tendons don’t do well with static stretches (in mid portion and insertional Achilles Tendinopathies calf stretches usually irritate more than help. Despite this they are often prescribed). My experience suggests, stay away from static stretches for tendon issues.
2. Most tendons responds very well to slow, heavy resistance training / loading (many cases of AT - especially midportional AT - respond well to progressive heavy loaded eccentric heel drops - bent and straight leg).
3. Appropriate amount and intensity of movement will keep the tendons pliable and nourished with some blood. Reduce the volume and intensity of movement to a manageable pain level (3-4/10) and slowly progress it. Make sure you have an adequate warmup prior to more intense movement (I always spend 5:00 walking before moving into a jog and then 15:00 jogging before increasing my pace to a run). Morning pain and discomfort are normal as long as they aren’t intensifying. Delayed or absent pain in the morning suggests improvement. I knew I was progressing when I didn’t have discomfort when stepping out of bed the morning after a run.