My Boyfriend Has Taken Sertraline 100mg For 8yrs. With His

My boyfriend has taken Sertraline 100mg for 8yrs. With his Dr. permission we decreased it to 50mg. Its been four days, but his blood pressure has risen very high readings like 190 over 105. We went to the ER yesterday they did test, blood work, ekg, cat scan of the head, because of head pain around the forehead and eyes, all tests seem to come back normal. They gave him 0.1mg clonidine twice daily. I am wondering if this is just acquincedence (sorry I spelled it wrong) or is it the change in the dosage of Sertraline or something else? Thank you Pam