Can you tell me if i am a carrier of fragile x will my son have higher chances of down syndrome?

Unlikely to happen: The defect that defines your carrier state and could pass to your son is a separate risk from that of ds, not affected by the fragile x. At 35-36 you have a separate risk of about 1% of trisomy 21, while your risk of passing the abnormal x to a son would be 50%. This is the same for a ds daughter with a similar (50%) risk of passing the carrier state to her.

No, risk of both: If you or dad have a blood relative with Down, your risk at delivery is 1%. if none, at 37 the risk at term is 1/226, and before 14 weeks 1/52 (many affected die before term). Risk for a male with Fragile X is ½ males, and for a carrier female, ½ females. You may have CVS to determine both. If termination is not an option, you may have preimplantation diagnosis for both, or a donor egg.