 [ Symptoms ] if you have sex on the 3rd can you tell you are pregnant by the 18th [ Disease ] you need to get this checked out by a medical professional as soon as possible the symptoms you describe could be due to an infection or a blood clot and both of these need to be treated quickly either call your doctor is office and explain to them what is going on so they can get you an appointment soon or go to an urgent care facility i am hoping the underlying cause of your symptoms is nothing serious but please do not delay getting this checked out all the best to you