Hypothermia ?

I live in Wisconsin Im a 48 yr old man who runs Marathons also compete Snow shoe racing consider myself in Excellent shape . Yesterday I ran outside about 9 miles temp was about 50 f Then later at night after supper I went to a YMCA to run laps as I was I was feeling very sluggish and I contributed to what I had ate Ribs . I had wanted to run 2 more miles but didnt feel up to it . I then lifted weights for about a 1/2 Hr and was feeling very tired . As I was walking out of the Y I started to shake or shiver I had considered stopping at the Main desk to see if they could find a warm place for me to sit but decided if I could make it to my Jeep crank the heat I would be better . As I ran to my Jeep in cool temp of 5o something my legs felt tight . I made it to Jeep turned on heat then really started to shake I called my Wife for moral support and after drinking some water I had and the shakes went down alittle I statred to drive home about 10 miles away . My fingers and toes were becoming numb also . I also was very scared and was afraid I was going to pass out , it actually hurt alot . I did get home and immediatly had my wife ready with water as well as starting hot shower . I couldnt get my cothes off so got in the shower with them on Minus my shoes . Drinking water and the hot water seemed to help esp on my head . After sitting in the shower for about 25min I was able to get a couple of layers clothing on and jumped into bed under covers which also helped and drank more water later early morning I did sweat more than usual . Im guessing I had hypothermia . So I did research on it and it said no Hot showers in Bold Type . Why ? Also how close was I to being in serious trouble last night ?