Husband has bleeding and scabbing shins, suspect low blood platelets? could this cause bipolar symptoms?

No connection: It is possible that in addition to whatever blood or skin disease he has he may also have emotional problems, but there is not a causation relationship. Also, who suspects low platelets? It's not a good idea for him or you to Dx. Training is needed to do this. He should have a good exam and use the results to decide treatment. I hope he gets these under control so you can enjoy life.