Did i cause myself a huge risk by getting a ct scan one n oct one in nov & one in dec of the brain is that a high risk for a tumor to delvelop?

No: It is always advisable to minimize the amount of radiation exposure, but what you describe is low risk. There are hospital patients that routinely get ct scans of the head on a weekly basis for a month at a time. The other option would be to ask your doctor if a brain MRI would provide the same information as a ct; the advantage with MRI is that it doesn't have radiation.

Very unlikely : Modern ct scans have very little radiation exposure and having two does not raise your risk of developing brain cancer significantly.