Without knowing more, I can suggest a few possibilities.
Dehydration; this will cause in increase in heart rate, a change in blood pressure, a lack of pump and a feeling of lethargy. This is the easisest to rule out if you are drinking plenty of water throughout the day. (By the way, if you think you are drinking enough water, add about a half gallon to that to be sure)
Overtraining: I won't go into it to much, but you sure mentioned some symptoms of it. Try a week or two of rest, maintain nutrition, hit the weights again and see how you feel. If this cures it, revise your routine to include more rest, decreased intensity.
Reaction with sugar; I'm stretching my knowledge here and guessing. However, for some with diabetes, a large intake of sugar will make them sluggish, thirsty and have a rapid pulse.
Tell us more about you: Age, height/weight/BF, general conditioning, training experience. Are you sweating excessively when you train or otherwise? Have you had a recent physical?
Also, good general advice is if any symptoms persist more than two weeks, see a Dr. If this is not just a training issue (and hell, even if it is) it may be, or become a health issue.
Good luck, take care of yourself.