Urinary infection can cause a sensation of pain in the lower part of stomach with constant sensation of pressure which you may be perceiving as sensation of baby being very low. Infections can lead to development of labour pains prematurely causing delivery of a preterm infant. As I am not aware of your exact gestational age, I would suggest you to visit your gynaecologist once as early as possible and get yourself examined and also treated for your urinary infections. Try drinking a lot of fluids and water as it helps in control of infections.