Most people confuse back pumps/pain with the kidneys. If you'd fucked your kidneys you would know about it.
If you've just finished using orals then i would take a break from them for now.
Always best to rotate orals, typically 4 weeks on 4 weeks off is what i've always heard. Mr Big gives some good advice on how he uses them in another thread.
If your in doubt always get your bloods checked by a doctor, there's a lot of shit and unnecessary fear mongering thrown about on bodybuilding boards about orals.