Detection methods are going to depend on the type of parasite you have, some are easy to identify some are not that is why you have to find qualified people to help you. Some stool tests may pick up the problem but again that depends on the parasite.
Any infection is going to cause problems such as chronic fatigue, joint pain, neurological etc.
Proper identification will determine the course of Antibiotics since there are many different treatments and usually they are multiple drugs. Some can be resistant to some meds, again this is why it is necessary for identification.