What Causes Tiredness, High BP And Severe Cramps In Legs And Arms?

Hello, my name is Krystal I am 24 years old, and I need new medical advice. Let me start out by saying i have always had medical issues since i was born. I was born 3 1/2 months early 2 1/2 lbs. I had asthma, seizures. As I got older I developed what some would say a nervous stomach i was going to the bathroom way way to often. I have lived in Las Vegas Nevada since 2002 and my health over the time has gotten worse. I stopped going to the restroom all the time and now im constipated, I was tested and I borderline celaic, and i have GERD, internal hemmorids, Beta-thalassamia-minor, acid reflex and cysts in my uterus. NOW FOR THE MAJOR CONCERN. All through high school and a few years after i was 5'3" and weighed anywhere from 120-145. The past couple months I have devoloped things no doctors have answers for out here. I am constently tired, I went from 127 to 100 in thirty days. I have not been able to gain weight period, i get cramps in my leggs and feet, i could be watching tv and my heart rate will reach 142 and the other day i blacked out for a minute. I am constently cold and irritable and out of no where my short term memory has been really bad. my ferritin levels are at an 8 the lowest they ever been my hemoglobin is at 10.4 and my red blood cells have gotten a little bit bigger though, I genreally have low blood pressure. I am really looking for some extra help and I am at a loss I am only 24 and I feel like i am going crazy because doctors in Vegas are at a loss. I am tired of seeing specilist and getting no where. Also, I've had a distending gallbladder and pains under my bottom left rib swelling. Please if someone can help me out I'd be grateful

Thank you,
Krystal