£200 later, and the tests have come back positive for house dust mites and food dust mites!  Apparently mites get in the dry food, and this tested slightly higher.  However the readings are under 500, and the vet says usually start vaccinations at 1,500.

Vet originally said we will order vaccine up now and keep him on the antihistamine (Antarax).  I said I wanted to try and hold off vac (I'm wary about going straight to chemicals for this and being told for life etc.) as I wanted to try more natural path first, given he is only showing slight allergy at this stage, and he is under 2 years old.  I already told the vet I wasn't going to use more steroids on him, and I'm glad I did this, seeing he is at the lower end of allergy

Vet agreed then (which made me more suspicious really) and said fine, and told me more precautions re. dry food, cos again I didn't like her suggestion at going to all wet diet.

Bottom line is I'm already doing most of the things required for house dust mites, and will be doing more on the food dust mites - like wiping his mouth after eating (it's just he always wiped his own mouth - on the carpet!)  I'll decant the food from the sacks to store in bin type thing, but wonder if this is enough seeing as mites are already on food?  I've also trimmed his beard - poor wee soul - didn't want to do this, but if dust gets in his beard makes sense to keep it short.

I'm going to be looking at diet although as stated previously he is on JWBeloved, and look at building his immune system.

So if anyone has good suggestions re house dust mite elimination, or good supplements for immune system, these would be most welcome.