I'm sorry to hear that Ash is still sneezing and is worrying you. Hopefully it's just allergies and his sneezing will go away very soon.
My Sunny and Sky sometimes get sneezing attacks and it turns out to be nothing. Storm was sneezing last night and this morning but is acting normally so I'm trying not to worry. It's so hard not to worry about our furkids though so please try to remain calm. Maybe you should call your vet and let him know what's going on. Take care.