On STD but no paycheck for 7 weeks

My husband has chronic back pain/sciatica. His employer started having "morning stretching & exercising" for employees before starting their shift. It had already been voiced to his supervisors and beyond that he wasn't able to do them without hurting. He was told one morning that the CEO said he had to do them anyway. Not wanting to be fired for insubordination, he did as he was told only to end up in the ER unable to move. He was then put off work on STD and then had to have surgery on his back which caused him to be off work longer. Upon returning to work, he was able to transfer departments to what we thought (according to the job description) was going to be lighter duty for him. This was not the case, the job was just as strenuous as old one. On his 3rd day in the new dept his supervisor took him to HR for a meeting stating it was obvious to him that he wasn't physically able to do the job. He was not permitted to return to old job but told he needed to be off for 6 mos. on STD then 12 mos. on LTD and then reevaluate. His employer has an outside company handle their STD. They have jerked him around for 7 weeks now about not having the correct paperwork from his docs and are now requesting all of his med records. Can they do this? In the past they have always accepted a form the doc fills out but now that's not good enough? I might add that his employer has now switched to a different company for STD. After several phone calls to STD company and his employer, my husband stated maybe it should have just been a W/C case and was told by person in HR "we don't do that" and "we are not having this conversation". In his latest conversation with HR today he was told "if you want paid you'll give them whatever they want". Is the STD company giving us the shaft because they lost the employer's contract? Since the middle of Dec we have called the STD company over 16 times only to be told that sometimes their voicemail doesn't work and they didn't get his messages. We are now 7 weeks without any paycheck and are now being told they might not give him the "back pay" for those 7 weeks. Can they do that? What should we do as the bills are piling up?? Thanks.