High heart rate & thick blood?

I went to Dr other day to get my thyroid lab results & he said I'm at high risk for heart attack because my blood is way too thick & thyroid is messed up again (i'm hypothyroid)..my heart rate at appointment was 121 when I was just sitting around..not doing anything strenuous at all..blood pressure was like 134/95...could my thyroid being messed up be the reason for the thick blood and high heart rate? I don't have an infection but I lost my baby at 5 months on April 11th & had a bad infection in my uterus & bladder then & was on antibiotics almost 2 months (clindamycin). I have an incompetent cervix is why I lost baby early & the infection at time. I'm 21 year old female btw. Also dr put me on baby aspirin at bedtime & a weight loss pill called Diethylpropion. He said it would make me lose weight, feel really good & lots of energy. I weigh 173lbs & 5'4". My question is what could be causing the high heart rate & thick blood?