Could it possibly be that the two things are unrelated. The cellulitis should respond to the antibiotics howevr they may be giving him one that is not effective and needs another. The pain and twitching sounds like a pinched nerve. To know for certain he should be examined and maybe have an MRI. Good luck. I hope he feels better soon.
Did they tell you to use anti inflammatory for his cellulitis? Such as Aleve?
I'm so sorry to hear about your husband's Cellulitis. So you know, this is the adult Diabetes II forum. Your post really belongs in the Dermatology forum since Cellulitis is a skin related disease more so than Diabetes glucose/insulin related.
Is your husband hospitalized? To my understanding Cellulitis treatment may require hospitalization if it is severe enough to warrant intravenous antibiotics and close observation by doctors. Body and/or muscle aches are part of the symptoms.
I believe many diabetics get cellulitis actually.
My husband has diabeties and gets cellulitis because usually a diabetic's immune system becomes weak.
If the meds he is on are not working he needs to go back and see his Doctor, personally I would take him to hospital as cellulitis is very painful and spreads quite rapidly.
A Specialist treating my husband once mentioned to me that if my husband was going to contract cellulitis it would most likely come back about the same time every year.
Thus far every Christmas for the past 5 years he's had it. Also make sure to check your husband's suger levels, as unusually high levels of sugar in the bloodstream can spark a deficiency in the immune system and then the cellulitius can take hold again.
I was told by my GP that it's a form of Staph, but definately he should go back to his Doctor and discuss the situation further.
Good luck.