I have read that lice like to get into straw since it's hollow, I don't know how true that is , since I don't use it I like to use pine shaving the flake kind much more absorbent than straw or hay and I have also had ducks going on 10yrs this coming spring and they have never had lice or mites and it's mainly because they bathe so frequent it just a natural way to keep them off, so I doubt your has parasites just molting which can take several months to get through,. I will say even when we had a mite infestation last year in the chicken coop my ducks/geese did not have them. I do under stand about stressing though we want them to be healthy.After reading this it really does not sound like he has lice/mites at all. I checked him thoroughly last night and could not find a thing.
I am starting to think he is just moulting. Last night he had a blood feather, I had to pluck the feather out. This is part of the moulting process isn't it?
I am starting to think I have stressed over nothing and he may just be moulting?
I am however going to seek advice from the local vet just to be safe as I am still too new at this. I will also change his bedding etc aswell.