Budgie's right leg dragging

My budgie, Charlie, seemed to be having balancing problems. Took him to a vet to get his nails clipped to see if that would rectify the problem. Now he is having problems getting around his cage. Can't decide if it is his right foot or something wrong with his wing but I do believe it has to do with the foot.

I have looked at his right foot and it does not seem swollen or broken. As he moves around it seems as if he can't get his right leg up when it slips off his perch or when he flies to another perch and his foot doesn't connect to where he is going. He then looses his balance and either falls to the floor of his cage or he needs to manoeuvre to get onto the perch he was going for.

He has a ladder in his cage and when he fell to the floor he went to climb up the stairs and he couldn't lift his right leg as he was climbing the ladder. His leg was dragging behind. The Vet did cut one of his nails to the point where it bled and she needed to clot it.

My questions are if the nail was cut to close could this be causing Charlie's problem? Could the problem be higher up on his leg and hidden by his body?

I have no problem taking Charlie to a Avian vet to be checked out, however, he does not seem to be in pain. I am a first time bird owner. Charlie came to me by fluke. He literally ended up on my front door step. I know very little about birds other than what I have read on the internet. I have read it could possibly be anything from a tumour to a sprain.

Charlie is not very tame and it is difficult for me to really have a close look at him.

Thanks for your help