My child is 9 has severe headaches always in front when she had her mri done they found a cyst in her sinus cavity what should be done. ?

Cyst: I don't think that a cyst in the sinus cavity will cause severe headache unless there is an obstruction. You need to see neurologist help make the right diagnosis

Depends: I would not think this is a cyst.It is more likely a nasal polyp and needs to be evaluated by an ENT.These can occur with allergic kids and represent overgrowth of nasal mucous tissue.There are some less common medical conditions that need to be ruled out by further study.