I think I remember when your husband first went on Remicade several years back. Sorry to hear he is having trouble again.
5mg sounds very low, I bet he is on 500mg, that would be more of a standard dose. I was originally on 400mg every 8 weeks. After going to 7 and then 6 week intervals, I had a flare up that landed me in the hospital. Once they put me on 1000mg every 8 weeks, things cleared up and have been pretty good ever since. I'd suggest having your husband get in contact with his GI doctor right away. Having symptoms come back so soon isn't unheard of, could just be a temporary thing, but let the doctor know. Even at 500mg he has room to increase the dosage if that is what is needed.
I know that even on my 1000mg I still have the occasional return of symptoms. Often stress is a big trigger, but so can a change in diet. Could be that this is just a temporary thing.
The others are right, research COBRA, that is a system where your husband can keep his current benefits for a few months after leaving his job. He doesn't have to get laid off for this to happen, even if he chooses to leave he can use the CORBRA. COBRA is usually good for a few months, I think it is 6 months. After that, he would need to find something else. Worst case would be he would go onto a government disability program. Not the best option, but at least he wouldn't go without any medical care.
I really hope things go better for you and your husband. I remember how well things were working for him a while back. Hang in there.
"I'm just along for the ride."