Sleep problem

My 3.5 week old baby girl won't sleep in a bassinet or any straight surface. It started couple of days ago and out of exhaustion, I put her next to me which helped for a day and half. Now she will wake up every 20-25 min even if next to me and would want to be held. Secondly, today she also seem to have been up for most of the day and now I am tired of her being overtired and facing difficulty sleeping in the night. Anybody rise existence this and have suggestions?