my pitbull is acting strange?

Hi, I have a ten year old red nose pit, on monday she started acting wierd, panting heavily, ears pulled tight back to her head, hiding when left along if she is with me or my girlfriend she is glued to us. Have taken her to two different vets one says it joint pain and gave us painkiller changed nothing and the second vet said she was scared of the storms we have been having and gaves us some anti stress tablets, they have made her less stressed but her behavouir has not changed. Has anyone else seen these symptoms?
The vets seam more concerned that she is not becoming aggresive something that she has never been.
I think she is in pain but cannot find anything that could be the cause, it very hard to see my girl in such distress she has been a totally loyal companion since we adopted her from death row ten years ago.
Any help would be great.
thanks

Aww I'm sorry to hear this, I haven't experienced it I'm afraid, would have suggested a vet trip but seems that hasn't helped. Has anything in her routine changed or anything happened that could have unsettled her?

Thanks Sazzle, we did start oiling the tiled floor in the other half of the house, we started on Monday the same day her funny behaviour started but we have done this type of work before with the same oil and with the same parts of the house blocked off from the dogs. We have finished the oiling now if its that that has disturbed her than all should get back to normal this week hopefully, if its not that its back to another vet in toulouse who is very good.

It could be a pulled muscle has she slipped/over stretched on the oiled floor? I was convinced Ledger had done that a few months back he still wanted walks etc as usual but wouldn't go upstairs would just look at them and cry I checked him as fully as i know how and couldnt find a sore spot so took him to the vet who half heatedly checked then gave antibiotics saying it was probably a digestive problem!

Since then every now and then he will be stiff/have a limp after he's has a good run with the ball so I'm convinced there is something muscular but still can't find that tender point of cause

Monitoring ATM but have a friend who is effectively a dog chiropractor who I will go too if it flares up again

thanks Jshrew, they have not been allowed into the part of the house that is being oiled and apart from that she has not fallen and is still keen on her walks and goes up and down the stairs no problem.
She is the most relaxed when out on a walk so maybe its the smell of the oil but we have used the same oil before and it is a bio product with very low levels of solvents that why we are using it.
The floor willl be dry tomorrow and life can get back to normal and we will see if she returns to normal as well, the ADAPTIL is helping with the stress so I will keep her confortable and wait and see.

Cookie is feeling alot better today much more her easy going layed back self. She is still a little bit stressed but alot less than last week, we took her for a day out yesterday and she had a great time nicely playing with some cats a big softy at heart.