What Causes Constant Dull Ache On Both Sides Of Abdomen?

Hi, I'd like to find out a little more about some symptoms I have been experiencing lately. I am a 40 year old mother of 2. Well I turn 40 this year. After my last period which was mid-Jan, I continued to experience a dull achy feeling in my lower abdomen. It ws more pronounce on the right side so when I visited the doc, he thought it could be an early onset of appendicitis. When I went to A&E and did a blood and urine test, the doc just told me that I have UTI and sent me home with anti-biotics. However, the ache still persists till today. It's a dull ache and actually I have it on both sides but stronger on the right. I have been feeling an increased feeling of needing to urinate and I have been urinating frequently. Recently, the past week, I developed stomach cramps and diarrhea for no reason. It's not like watery stools but very soft at time and watery at times. I seem to have like a lot of gas in my stomach, especially when I need to pass motion. I have been feeling very tired in the last couple of months that I find it more comforting not to go out and do things but to stay home and relax. I have been sleeping more in the past few months during the day when I normally am unable to do so. Could you advise?