A few weeks ago I trim my little Shih Tzu Tail where it had matted next to his little rump. He goes to groomer every few months so he is used to being groomed.
His tail was quite bushy but after i trim it down he acts embarrass and always trying to bite his tail.
Any idea why he would be doing this? I have checked him over for any cuts or sores but he is clean.
Thanks for any help/

I doubt he's embarrassed. There are several reasons he's biting at his tail, though.

If you bathed him he may have shampoo residue which causes itching.

If he was tightly matted, trimming the mats away might leave the skin feeling strange and sore. Kind of like having a pebble in your shoe all day. Once you remove the pebble, your foot feels strange, and may actually hurt more for a while.

Are you certain he doesn't have fleas? That's a common cause of dogs biting at their tail and rump.

It could also be his anal glands.

better have patience..i know that is embarrassing but patience is the way to improve it..

Thanks for replies.
I treat him each month for fleas and also give a capstar every so often. But
i know he could still have them.
Will keep a close watch and keep check regularly.