The FloodReady Website is a network of stream gauges across Lycoming County which helps residents track the water levels in our creeks and river, current rain fall information, and history of flooding at various gauges. This site gives near real time readings and helps residents prepare in the event of flooding.
The half life of doxy is 18-22 h. Since you took four days' worth, you were in steady state. In five half lives 95% of the drug would be eliminated, and in 7 half lives, 99% is eliminated.
I recommend waiting for 7-10 days. By that time all the doxycycline should be out of your system. The half life (the amount of time to eliminate 1/2 of the medication out of your body) of doxycycline is 18-22 hours, which means that after 1 day only half of the medicine is left, after two days 1/4, etc. Essentially by the end of the week, pretty much all the medication should be gone.