Hi there,
Thank you for that information i now have a better idea of what i think may be going on. Because of how this problem started i think this may be more of a anxious problem than anything else and may in part be due to some level of separation anxiety.
Yes, bring the crate back in. You probably won't need to start training all over again but until he is more confident and better trained it will save you some problems
Put the crate in a quiet warm area where he can feel safe. He should be comfortable enough with the crate to want to go there when he feels anxious.
Always leave the crate open and try and put some toys in there to help him adapt back to it. You can choose to completely recrate train him or otherwise watch for the signals that he gives that he needs to go to the toilet. These may be very subtle like following you, vocalising etc if in doubt take him out
As for the odour neutralisers try as many products as possible some work better than others.
now for the anxious problems. Rusty should never be rewarded for any signs of being timid or afraid. This includes cowering, backing away etc. Don't look at him, don't talk to him, don't pet him. COMPLETELY ignore him. But the second he starts to show some confidence eg standing up, coming out from hiding you must reward him. Quietly give him attention and praise.
If your husband is part of his separation issues then he needs to have as little to do with Rusty as possible. He should not feed him, walk him or train him. This should all be done by you, you may have to take Rusty with you during the day if that is at all possible. When your husband and you come home from anywhere ignore him for the first 20 minutes no matter what he does. Then you may have low key attention with him, don't get him worked up and excited.
At the weekend try and ignore him for hours at a time.....especially your husband!
It will take some time to build up his confidence and during this time you can feel really mean and get frustrated by the whole thing. But be patient and work hard at reinforcing confidence and ignoring submissive or anxious behaviour. Please let me know how things are going and i will try to help further if possible.
Good luck
Kind Regards
Todd Field
Kingdom of Pets Team