Thanks The pet shop did tell us they was from the same litt. But they also lied about other things. So hopefully, being from the same litt is a lie.

We got him booked in, the vets said they will have to sedate him to do some heart scans. Its a nervous cat, seems to be comming out of its shell more now the other one isnt around to bully him. I hope it goes ok, if he does have a heart problem too, he will get very scared/nervous when we take him, which could make his heart worse! but it has to be done. I do not want anything to happen to this one!

Thanks again