Re: Always sick it seems!
Optimum body fat and good conditioning should make you sick less, not more. Very low body fat can compromise your immune system, however. Unless you have ultra low BF then this probably does not apply.
You could be more vulnerable to colds etc. than in the past due to overtraining. If this is the case, adjust your training to allow better recovery. Also, you could be exposed to more forms of colds etc. than in the past from jiu jitsu, or your CF gym.
Those seem like two possible contributors to your experience of being sick often.
Another tip is that whenever you enter a new germ environment (new job, new school, new group of people), it is common to catch a cold or something from the group. The group has already contracted and become immune to one or more types of cold, but you are being exposed to all of them at the same time. This usually happens in the first couple weeks only, so not applicable to your entire experience.
Wash your hands, take a multivitamin, maybe some extra vitamin C, get enough sleep, and you are doing everything you can I think.
Hope this helps!