High blood pressure, intense colds, minor chest pains and feeling light headed, went to ER all ok, what can this be?

About a month in a half ago I recorded my first reading of high blood pressure 148/89 after experiencing minor chest pains and feeling light headed. Two weeks before the first event, I was at the docs for my 2nd intense cold in the span of 2 weeks with no recording of high BP. I went back to the doc 2 weeks later for the same exact feelings and recorded BP around the same reading. I was given an EKG test, blood work, and a 24hr holter monitor. All of the tests came back normal, blood work was excellent. The week after I ended up in urgent care and then the emergency room for feeling the same way but I recorded a BP measure of 164/94. All of the tests came back normal as well, EKG and blood work including a chest x-ray. I did have 2 low readings in the past month which were 142/78 and a 138/76 in the ER. I followed up with my doc and he put me on HBP medication lossartan potassium 50 mg but switched me to Hydrochlorothiazid 25 mg due to feeling the side effects i.e. light headedness/dizziness and headache. I am a 23 year old male, 6’1 185lbs, recent college grad also played a sport while in college. I go to the gym regularly and eat a lot of fruits and vegetables everyday but I don’t train like a college athlete anymore. I don’t smoke or do any drugs nor take supplements. I do drink like I’m still in college but only on the weekends. HBP does run in my family along with diabetes but HBP did not develop in the fam members until later in their lives. Intense anxiety did overcome me after my first HBP reading(so for about a month of straight anxiety everyday) because I simply thought the next time I workout I would drop dead, so I stopped going to the gym until the week of Christmas. I feel great when I workout or go to the park to play the sport that I love. I just want to know what could cause this because it literally feels like it happened overnight and I really do not want to be on medication.