Hi there, welcome to EBN.
The yellow crud on his nose.. is that discharge? Because it doesn't look like it.
The rash though, you need to put something on it. It may be an allergic reaction to a plant, grass or whatnot. I know Blue sometimes gets red around his privates if he squats for too long in grass.
My vet gave me "Betagen Topical Spray" that I've used for rashes, and such. It's really helped. You can get it online too but I think it requires an Rx from your vet.
Since you said he's acting the same way as when he had a blockage, the first thing I would do is take him in for a sonogram (I don't trust x-rays). You really want to rule it out.