I can speak from experiance, I'm seriously considering quoting lifting totally.
I noticed this for a while now that I constantly got sick throughout the years often right after a heavy workout.
Due to working 72 hours a week, I hadn't lifted in about 8 months. Not once during that time did i get sick and this was while being around sick people frequently including my toddler son who as children do got sick a lot.
Worked out on Monday and Tuesday after an 8 month lay off and bam, I'm Fuckin sick on Thursday.
Pardon my grammar, cold meds plus posting from a phone don't mix.