i'm not sure your leg infection has anything to do with MS.
DO NOT stop taking your antibx before the end of the course. the infection could come back or flare up and cause a worse infection than you originally had.

i'm surprised they didn't give you IV meds, at least to start.
please watch your legs carefully to make sure this is getting and staying under control.

also, i wonder if a dermatologist could help you keep your skin in better condition so you don't have dry and breaking down skin that could allow bacteria to enter.

also, it might be good for you to try and keep your legs elevated. that's better for edema, swelling and might help keep better circulation in your legs.

please let us know how you're doing.