Exercises for someone with muscle deterioration?

So I have some muscle deterioration as I'm sure you've figured out. I have a chronic illness that is somewhat under control with medication right now but I was very sick and mostly housebound for over a year and have lost almost all of the muscle I had and have gained back a lot of weight.

I used to exercise daily - yoga, HIIT, pilates, cycling, 30DS. I was a go hard or go home kind of person and now with my vastly weaker body and scoiliosis and bad joints (I have hypermobility syndrome) I'm at a loss as to how to start easing myself back into exercise to restore my muscle, lose weight, and get healthy.

I have some limitations because of my illness, hypermobility syndrome, and scoliosis, and of course because I'm basically a weakling right now. I really need to strengthen my hips, core, and shoulders.

Any advice is welcome! I have access to dumbbells, yoga stuff, an exercise bike.