There are a couple possible causes for your symptoms. The first (and most likely) is that you have developed a urinary tract infection. This is a common problem in young women and even more common after sex. The typical symptoms include burning with urination, frequent urination, urinary urgency (the sudden urge to go), and sometimes fever. Irritation of your urethra without an infection is also a possible cause of your symptoms. This would be the case if you are not typically sexually active. If the problem is the latter, then your symptoms are likely to go away on their own very soon. If it is the former, then you will need antibiotics.
I suggest that you schedule an appointment with your primary care physician
. He or she will want to know more details about your symptoms and perform a thorough physical exam. In addition, your doctor
will take a urine sample for a routine rapid urinalysis. This should be enough to tell whether or not you have a urinary tract infection. If you don't have an infection, and your urinalysis is otherwise normal, then you may need a referral to see a urologist
. This is a scenario that would be unusual, as I expect your symptoms to resolve rather quickly.