Lmp 4/8/15, took pregnancy test on 5/11, passed a couple clots on 5/12 with abdominal and lower back pain. beta hcg quant done on 5/15...level 48. ?

See OB ASAP: See OB. You maybe miscarried or you may have a non viable pregnancy or simply first trimester bleeding. The way to find out is to have an OB perform a transvaginal ultrasound. If there are fetal heart tones, then close follow up is needed. Do not go on any long trips or travel by air or out of a metro area where health care is accessible in case you do miscarry and bleed heavily.