Just got to see the picture you had sent. This is not blistering secondary to a burn - such blisters never spread all over the body and stay localized to the burn area and you have clearly mentioned that you husband had skin lesions all over his body. Furthermore blisters indicate superficial burning and form within 24 hours of a burn, not after 15 days.
Your husbands history is very suggestive of an autoimmune blistering disorder like Pemphigus Vulgaris (PV) or Bullous Pemphigoid (BP). For reasons not clear as of now the patients body starts making proteins known as antibodies that target molecules in the structural framework of skin. This causes the skin cells (keratinocytes) to lose attachment to each other resulting in a skin blister. There are numerous autoimmune blistering skin disorders. A bullous reaction to the drugs he was on in the hospital would be a second possibility - this is called a 'Bullous Drug Eruption' - however this should not have flared after he was discharged and the drugs stopped. So an autoimmune blistering disorder would be the first possibility.
What is required right now is to take him to a Dermatologist for a skin biopsy - this will need to be sent for tests called 'Histopath examination' and 'DIF'. The results usually take 5-7 days but presumptive treatment can be started immediately after taking the skin sample. A blood culture and skin swab for bacterial culture should also be send to rule out blood infection (sepsis).
Mild to moderate bullous pemphigoid can be usually be managed on potent topical steroid (Clobetasol/Halobetasol) creams alone. These should be mixed with an antibiotic cream before application (twice a day). Oral antibiotics like Doxycycline/Tetracycline can be given for their anti-inflammatory effect as can other non-steroidal/non-immunosuppresant adjuvants like Dapsone and Nicotinamide.
For the itching, which can be quite severe in BP, start him on Tab Benadryl 25 mg three times a day or Claritin 10 mg two times a day. His skin must also be kept well moisturized. Stop using soaps for bathing, instead use a soap free body wash and luke warm water.
Regarding the dressing of open sores: Open sores resulting as a result of blisters bursting should be covered with a paraffin gauze+antibiotic cream dressing for faster healing and preventing secondary infection. These should be changed everyday.
For patient's who do not respond to the above oral steroids need to be started in a dose of 0.5-1.0 mg/kg body weight. A steroid-sparing adjuvant like Azathioprine should also be started along with oral steroids. The steroids usually provide excellent control within 1-2 weeks after which they can be gradually tapered off over 4-8 weeks while continuing the Azathioprine for 3-6 months to prevent a relapse. Both of these drugs can make a person susceptible to infection so your doctor will need to monitor your husband with regular blood tests during the course of treatment.
Please feel free to ask if you have any queries.