Welcome to the forum. When you are pregnant the foetus produces a hormone, HCG
. This hormone passes in your urine. Ordinarily pregnancy
test kits can detect HCG in urine between 10-25mIU/ml. But if you have miscalculated the dates of your cycle or if there occured some error while performing the test it can show false negative results.
Wait, if you get your periods within a few days fine. Else you should repeat the test in the morning with midstream urine for accurate results.
Backpain can be due to muscle, tendon, nerve root
strain or compression. You can apply pain relieving oitments/sprays. Exercises are beneficial. Avoid lifting weight and sedentary lifestyle.