Hi @immarojas! Yoga is the best option I have found for fixing sciatica, which is often caused by a tight or inflamed piriformis muscle. Here's one good stretch for that:
https://steemit.com/health/@saramiller/how-to-yoga-reclining-pigeon

With shoulder impingement, I suggest avoiding sweeping the arms overhead in yoga or pilates poses until your healing progresses. Instead, you can keep the arms in the forward plane without reaching overhead.

In both cases, your discomfort may be due to inflammation, so I would definitely suggest adopting an anti-inflammatory diet--lots of greens, turmeric, ginger, and other plants.

Pilates offers lots of benefits to the body, but I personally do not have extensive experience with it.

I will make some future posts to address your questions a little deeper. Thanks for asking!