If I have reactive c protein could this mean that I can have reumatism?

Not work that way. CRP or c reactive protein can be elevated for lots of reasons: infections, heart disease risks, obesity, inflammatory arthritis, so forth. It does not causes rheumatism but can be a consequence of rheumatic problems. It is not the cause but rather the effect.Crp.
Not necvessarily. C-reactive protein is a test for inflammation. It is non-specific. It is used to evaluate one for arthtitis and is just one tool. There are other blood tests, x-rays, and exams that will make the diagnosis of ra. Make sure you are communicating with your pcp or rheumatologist about your tests, testing and work up.