Hamlin dehydrated, taken to infield care center, is OK:

Late in the race, #11-Denny Hamlin reported feeling ill in his car (finished 8th) at Charlotte and complained of a severe headache. He was taken to the infield care center after the race, and team owner Joe Gibbs said his driver was dehydrated, was given an IV and was feeling better after the treatment.(NASCAR Wire Service)
AND‚ comments from Hamlin:
Q) How are you feeling after visiting the infield care center after the race?
Hamlin:‚ “A lot better now. I knew when my knee was sore afterwards that it was probably fluids. My off-day was 36 holes of golf and a full tennis match. Probably over did it a little bit this weekend. I think the dehydration led to a migraine and just felt nauseous the last 100 laps or so. Thank goodness, that didn’t cost us the win. Just the bad end of that strategy and what not, but still proud of our FedEx Office team for really giving me a car that could contend for a win. This is a good sign and congrats to Carl (Edwards), this is an awesome two weeks really for our organization.”
Q) Was it difficult to finish the race feeling like you did?
“It’s tough, I was borderline throwing up trying to race for the lead. You just try to power through it and of course when you run well, you always feel a little bit better, but when the race is over and everything comes to a stop you realize how bad you feel. A lot better now with fluids and everything. It was directly related to hydration.”
Q) Was it challenging to come back from the loose wheel?
Hamlin:‚ “That part of it stunk a little bit, but the 78 (Martin Truex Jr.) came back and passed us anyway. When he came back out, he had fresher air than what I did. I came out kind of middle of the pack and just couldn’t run the lap times I needed to. Those guys ended up on the bad end of the strategy anyway.”(Toyota Racing)(5-25-2015)