Lately after riding my body temp has been spiking. Even though I've cooled down completely and showered hours before I begin to sweat again and start to feel "sick." This happens about 5 or 6 hours after riding and usually after my weekly long ride (70-80 miles). Eating or not eating doesn't seem to make any difference and my rides have been this length for over a year with no other effects prior to this starting.
I feel fine until it happens but once my temp goes up I feel exactly like I have a cold or the flu. Sweating and feverish. Sometimes with light nausea and I definitely do not "feel good." My normal temp is 97.8 which is a bit cooler than average but it's my normal. The last time it happened my temp was a bit over 99* several hours post ride. This lasted throughout the night until morning.
Is there something going on here that I need to worry about? Or is there something I'm not doing that I need to be doing to ward off this post-exercise rebound? It's been getting worse after each ride for the past 2 months or so. Nothing before that.