I agree with Secretum they are intrusive thoughts fueled by anxiety and paranoia.
There is no doubt behind a delusion, unless you have the same strong convictions tied to experience/thoughts as having a hand on your arm it isnt psychosis.
I have obsessive compulisive traits, allot of people with bipolar do, the intrusive thoughts can be tourtureous.

I also become floridly psychotic when manic. Memories when delusional become irrational and wrong or off overtime but they still share the same truthful reality feeing associated to things like 'water is wet'. I have a complete lack of insight while manic and/or delusional. Its still a hard concept to grasp having no idea when your insane instead i verbally and violentlly refuse it. Rejecting, family, treatment, authority figures, logic, food, sleep and the shadow peoples attempts to steal my thoughts of meaningful discoveries. Help, ill and sick were codewords in conspiracy to silence the truth after i escaped the water tower inspector who came to work to poison me for not broadcasting happy thoughts over the radio.