Is A Biopsy Needed For Moles? Burning Sensation And Cramps In Lower Abdomen. Could You Tell Me What It Is?

i have had moles appearing on my body quite rapidly the last couple of weeks, it started on my neck and a few more then appeared on my face, i already had two moles there that iv had as far back as i can remember, however one of them has risen and changed shape and is no longer symmetrical, at first i never took much notice as i have eczema pretty much all over my body so every so often i will break out in dry itchy skin , but a few weeks ago, the left side of my face where the mole that has changed shape really started to itch aswell as a part of my skin with no moles, but in the last few days a mole has appeared where my skin was itching really badly and there wasnt one there before, iv been to see my GP and she said she will refer me to a dermatologist to have a look at them and possible have a biopsy, the moles have started to appear on my torso, arms and legs now aswell as my back, i looked up what is could be online and apart from the obvious (cancer) it said it could also be down to puberty, im praying its puberty and that it will stop as i had a cancer scare last year but with my bowel as blood was in my stool and it had been going on for a year and getting worse, however now it feels as if im tearing at my rectum every time i go to the bathroom, its extremely painful and i have been trying to ignore since may last year as iv been too embarrassed to tell my GP that its becoming too much for me, but when i initially told her , i was referred to the hospital t to have an colonoscopy, im still in allot of pain and have been given a cream to take but im not feeling any changed, im just getting worse. My questions are: 1) is it possible to not have a biopsy done to find out if the moles are cancerous, or do they have to be biopsied, i am asking this as i am very nervous and uncomfortable with the thought of a biopsy being done on my face, if was any other mole on the rest of my body i wouldnt mind, i just find this a bit unnerving. 2) do you know what it is that is possibly wrong with my stomach, the last 3-4weeks i have been feeling allot of burning in my stomach and getting cramps in my lower abdomen, especially when going to the bathroom. i have just turned 18 and i am female, weigh is 15stone and height is approx 5ft7inch. Thank you.