Horse stalled due to pastern injury... other legs are swollen...

My 8 year old AP Quarter Horse mare is very accident prone. I found her in the pasture with a pretty deep cut right below her left hind fetlock. I am currently keeping her stalled because I have to give her penicillin and other meds, and I have to change her bandage every day. Today I noticed that her other legs were quite swollen. I am guessing it is due to her not getting as much exercise as she as used to. I am afraid it will hurt her to ride her.
Could the swelling be due to lack of exercise or something else? How can I exercise her without making the cut worse or hurting her?

Also... any suggestions for giving shots? She is VERY needle shy.

Stocking up is a very common side affect of a stationary horse.

Do not know the extent of the wound so can not advise you on how to provide exercise. What did the vet say? Is hand walking allowed?