Is Blood Collection During Early Pregnancy Dangerous For Me Or My Baby?

I am 13 weeks pregnant & have seen more blood (no pain, no clots) 4 days back. I got admitted in hospital, was under IV & injections & observation for 3 days.. I got discharged after blood stopped coming out.. In sonography it is said i have some collection of 3cm( but is not affecting baby right now, baby heartbeat is healthy & is moving healthy).. I had history of having same collection of few mm size in early pregnancy(around 10th week) and got dissolved itself (declared in sonography) was told that there is no harm to baby n me too.. I was advised strict bed rest at home( can move only for toilet & not for anything else) with some medication. Please can anyone explain this & guide me whether this is safe or not for me & my baby!??