Did I get sick from traveling to Costa Rica?

If you haven't already, go to the doctor, and if he doesn't suggest it himself, have him take a blood sample to test for malaria and Dengue Fever. The weakness, exhaustion, head and body aches, chills and fever are classic symptoms of both. Before you also have a panic attack, the P. Vivax strain of malaria that is common in Central America is easily treated and you should be on the road to recovery soon. There is no specific cure for Dengue. The symptoms are treated and you simply wait it out.