hi i was wondering if you could give me some adive on my dog

two weeks ago we notice that he was sliping hes bum on the grass and on the path outside my house. we thought it was worms so we wormed him. a couple of days after that he was still doing it and then we thought he might be hes glands so we took him the vets got his glands done. it seemed to work for a couple of days, but he is still slpiing hes bum have you any ideas on what is worng with him. i would love to hear from you. thanks for taking the time to read this hope to hear from you soon.

su