Hello today i've had a off and one headache sore throat and blocked nose and i'm very tired it has been from a severe headache to being un noticeable and i'm worried about it and what could it be and should i see a doctor?

Viral infection?: Although we can get some symptoms like that and on the next day the symptoms can be gone, with the current Covid and in view that you are young, just rest, drink fluids, take some tylenol or motrin. Isolate yourself, so you do not infect others and try to do a Covid test and more importantly, monitor your symptoms, your temperature, your activity. If in doubt, check with your doctor. Stay calm!!