Doxy sterilizes nematodes and helps control bad bacteria. If it was me I would continue with doxy . Doxy is normally taken for 30 days first time , 100 mg dosing twice a day then 2 weeks off and 2 weeks on for several months, I did this for about 1 year . Ivermectin can be taken everyday and is the recommendation for serious roundworm infections like strongyloides on steroids , but I preferred 3 days on 1 day off I did this for about 1 year. some do better with 2 days on 2 days off. Killing worms too fast can cause severe issues with health. ivermectin works slowly , doxy speeds up the worms lifecycle causing it to die prematurely . it is best to go slow and steady with worming then to go fast and furious . Slow and steady is the right pace for healing and eradication , fast and furious is very risky and can be severe if infection is severe. The worms ain't gonna kill you tomorrow but taking too many meds and mixing the wrong types can. Some infections like mine take up to 3 years to fully cure but that's according to the horse peeps (Thats who I trust ), Our modern high tech govt insurance Drs can't even find a worm , so how would they know how to kill them properly without govt insurance intervention , At the end of May 2016 will be my 2 year anniversary from daily to monthly lifesaving Rx wormers and I am Reaching the home stretch with my health fully restored well before the 3 years. I would not take any other meds but ivermectin and doxy if it was me and I would add Fenben after a few weeks.