Leo is not eating anymore

[Repti]

Seems like I have big problem.

One weeks ago(Tuesday) I went to the vet and my Leo, Rex, as worms. I'm not sure but I think she told me round worms. So she gave me panacur to give to him. I have to give him 0.2 mL of panacur one time per week during 4 weeks. I have to put the panacur into his meals. After 2 weeks she told me to change the substrate.

Wednesday, I gave him the first dose of panacur. I put it into a cricket. He ate it no problems at all.

The days after I was trying to give him meal worms and super worms but he did not want them. Thtat seems very weird for me because normally he loves them.

Yesterday I was suposed to give him his dose but he wasn't hungry, He refuses a meal worm.

Today, Thursday, He ate a meal worm so after I put the panacur into a pinkie and try to give him. He refuse it. After he ate a super worm and I try again to make him eat the pinkie. He grab it into his jaws, shake it, and let it fell. After he went in his hide.
Why does he don't want to eat? Is it possible that the pinkie smells the panacur and he doesn't love it??
Should I worried??
After what happenned to Samba. It seems like it's the same thing happenning to me.
I'm really freaking out. Please help me!
Any comment our suggestions would be great.

Repti