Anyone any experience of recurring viral infections?

tl:dr
So I picked something nasty up in late November/Early December. hacking cough, snotty, sinus pain. Eased after a few days and thought not much of it. It the reared its head again over Christmas, then mid February (bad enough for a day off work and a weekend mostly in bed) and again mid-March. By this 4th time it was more than coincidence so I resolved to drop race plans and cut back on pushing my body. Immediately took 10 days off running (7 days off exercise as was skiing at time).

I then started easy running, 3-4 days jogging then a day off (at about 50-70% of my normal weekly volume) for 3 weeks. A few runs got a bit harder when a running partner would push a bit. After 3 weeks of easy running I was feeling good so thought I'd see how a local 5km would go. The day after I had a sore throat and the next day was back to the 2nd worst I'd felt out of any of my bouts so far. Same symptoms as above

So I've been to the doctor for blood tests. No results in 1 week so assume there's nothing wildly anomalous. 7 days off running but still a bit mucusy in the throat. I'm upping my Vit D again (dropped off that once the clocks changed) and taking a bit more iron. Diet is generally pretty good - lots of veg, some fruit, cutting down on meat a bit but not super quickly. Bit too much crisp/desert comfort eating of late mind.

2 of my friends I was with the weekend I picked it up have had similar symptoms and reoccurrence patterns, but with less running.

Everything has felt pretty viral and the tiredness I get when i feel ill again definitely does so. HOwever waking resting heart rate hasn't been too high - when it is I'll cut back for the day - though I am aware of my hr getting very high when I jog on anything other than the flat (i.e. reaching about 90% of max) It's obvious that my hitherto bombproof immunity has been compromised - moved to new area and new job in October, then hit 3-0 soon after! Energy levels a bit lower but not feeling CFSy.

Question is do I ask for treatment of the virus or sit on my hands and ride it out as antibiotics could hit the body worse.