Here is some good info on the diuretic you are taking.
http://www.ehow.com/about_4695851_hydrochlorot-side-effects.html
Make sure you electrolytes are checked. Higher water intake means higher water output that could lead to changes in Na/K levels.
Could be your fluid volume is low which WILL cause this. Some people do not get thirsty and then there are problems. I am one of those, so I hear ya. Make sure you are drinking enough water and see what happens.
You are a little brief, lacking on information, for any confident or specific response.
But, I will say a HR of 101 isn't a problem if you are physically or emotionally active. It is a bit high if you are truly at rest when that HR is achieved. You didn't say what your blood pressure is, but the guideline I espouse is if you are not dizzy, have headaches or some other symptoms of too little oxygen getting around (sweating is another), then your BP isn't too low. I say that without knowing how low it is.