Hi welcome to Health care magic forum.
Thanks for calling H.C.M.F.
You are pregnant of 5 weeks, you had mild bleeding, and cramps in the lower abdomen. You had intercourse before that of course it has nothing to do with it.
Your problem is called threatened abortion, so you should be concerned about it , other wise there will be a possibility of inevitable abortion.
You are advised to take absolute bed rest
, and intercourse is prohibited completely.
I advise you to consult an obstetritian for confirming the threatened abortion
, and preventing the inevitable abortion.
Wishing that everything will be fine.