Head injury, concussion, bleeding in the brain, cold, headache, unable to focus. CT scan required?

About 3-4 weeks ago i rolled my car and got concussion , as a precaution i went into hospital and stayed over night in a neck brace the next morning they gave me a CT scan to check for bleeding in my brain and said there was a little but nothing to worry about and i was able to leave however weeks later i have got a cold , that is not worrying just chest and nose but i have also been getting this stuffy head ache and my eyes are struggling at times to focus causing me to feel lethargic, my motor skills and that seam normal apart from feeling a little dazed when my eyes wont focus. i have also had unusual sleep patterns due to stress at work. Please help, are there any symptoms i could look out for or tests for hemorrhages, also how reliable would the CT scan have been, can bleeding come back later even with no head trauma