Vanishing twin

Hi all I'm new to this I've just joined. I'm 11 weeks tomo and have had problem after problem so far first thought ectopic then once confirmed baby was in right place they discovered two sacs but only one heartbeat after 3 weeks of scans/check ups they said only one baby is growing and the other sac will just reabsorb. My question is has anyone else experienced anything like this. I've had quite bad pains and some spotting I'm losing symptoms on and off and just wondered if it's because of the vanishing twin as they call it. Any info would be massively appreciated. Thanks everyone xx