I have been burning when I urinate, having lower abdomenal and back pain and my sperm has become very thick it happens when I have sex and lasts for about 2 weeks

You should get check. This may be due to an infection. See your primary care and get evaluated.
Those. Those symptoms are very concerning for an infection. You may have urethritis, prostatitis, or a bladder/urinary tract infection. Please be seen for an evaluation. If you have worsening pain, fever or vomiting then you must be seen as an emergency.