Please bare with me as this post might be quite long! I just want to include as much info as possible.
So I recently adopted my dog 2 months ago and for the first few weeks he was okay and rarely scratching but he was licking his paws and legs. Since the beginning of August he has been constantly scratching the area near his tail and occasionally biting around that area. Along with the scratching, I've also noticed that he recently would start chewing on his paw and licks himself quite a bit.
I am using a flea preventative (Trifexis) but I'm afraid that with his most recent dose, he didn't take all of it because i tried sticking it inside some pumpkin and he spit out the tablet and the tablet began to crumble and there were some crumbs and pieces of the tablet that was still left on the floor that he didn't eat.
I've checked over and over again and found no signs of fleas or flea dirt, and although I have found black specks, when I sprayed water on it, it did not turn any shade of red. I have been vacuuming the house everyday for the past week as well. I've also tried bathing him and did not see anything that resembled fleas in the water.
Could all of this scratching be a sign of allergies instead of fleas?
I have been feeding him Hill's Ideal Balance slim & healthy (Chicken & Barely Recipe) and his poops have been solid but they are a little soft.
Thanks in advance!