Allergy in 3 year old

Hello
I hope someone can help. My three year old little boy has just developed a skin allergy. It started 3 days ago when he sat on a wool blanket, I think it is dust mites? I soothed the bites, red patches with vinegar and after about 3 hours it disappeared!! But it has reappeared several times since. Unfortunately it has not just been confined to the house. He has had a slight flare up whilst at the park.

He is 3 yrs of age. We live in France near the coast and the weather has changed in the last two weeks and is now colder, but sunny days. He has had 3 awful colds, and one ear infection in as many weeks and I am hoping that this is the reason why he might be showing signs of an allergy, due to a weakened immune system. His father has lots of allergies and asthma.

He is a out going little boy, with pale skin, blue eyes and blond hair. When he was born he had dark circles under his eyes and I was concerned about allergies then. He was and is and is breast fed. I am careful with his diet and he does not eat wheat/grain products, he does consume raw diary, but due to the colds this has been greatly stopped/reduced. His diet has not changed recently. He has never been on antibiotics or any medication.

The symptoms arise when we are in the sitting room, near the sofas. Or when he has been crawling on the sofas, (he has had the spots red and raised but with a white ring around them. Or a swollen red or white area. They do not appear when he is clothed. Although one of the main areas for the rash is on his hands and he has had a small rash whilst visiting the park (there are pine trees in the park. I treat the areas with vinegar or give him a vinegar bath and the rash subsides. His nose is blocked when the rash is there. I feel his nose is more blocked since this rash appeared, although he has had a cold. He does seem to be coughing more and it is more of a chesty cough since developing the rash, but this may just be the natural progression of the cold. The rash is itchy but once I have applied the vinegar he is not bothered by it and carries on playing. Luckily his breathing has not really been affected, or no more than an average chesty cough/cold. He is more clingy/crying but that could just be due to the colds. He is headstrong and knows his own mind. He communicates well. He was also vomiting at the weekend too. It lasted for 48 hours and could be related to the phlegm, I am unsure! I hope this is enough information to help his condition. Thank you.