Beardie has 3 parasites help :(

So my 7month old beardie had been acting lazier than usual for about a month, his poop started smelling terrible and really watery. I decided to take him to the vet a few days ago and the fecal test showed coccidia, gidaria and whipworms . They put him on a deworming treatment pancur,strongid and metroni. They gave him his first treatment there and said to come back in 3 weeks for a 2nd and in another 3 weeks bring in a fecal to see if hes better if not another treatment. Within the first day he started acting alot more lively so im glad hes feeling better but what could have caused it. I feed him dubia roaches and collared greens. I let him try a hornworm and also fed him black soldier fly larvave for about 2 weeks then switched back to dubias I also let him bask in my backyard for about 30 minutes every other day but i make sure he doesnt eat anything from outside.Sorry for the long post i just want to know what caused it and how to help him thanks for any help !!

It's possible that he's had them in low amounts since you got him but they were able to take hold and flare up recently for some reason. Those are good meds so hopefully they help quickly and he will be back to his old self soon.