Good afternoon, dear flower growers, please tell me what’s wrong with the calathea

 Good afternoon, dear flower growers, please tell me what’s wrong with the calathea - I bought a baby in a 6 pot in November, after my arrival I transplanted it into a 600 ml pot (I had just started working with flowers and didn’t know that this was a lot), for the first two months everything was fine, it grew leaves, then the leaves began to turn yellow and dry out (the tip and along the edges), I transplanted it into a more suitable pot. 

I spilled it with phytosporin. In March, a tick attacked and there was still something incomprehensible, I treated everything (Aktara in the soil, spraying Fitoverm + Epin 3 times, after 7 days according to the instructions, I monitored the result using a microscope), it became better, but only slightly, watering was adjusted (1- 2 times a week as the top layer of soil dries), the roots are alive, it is on the eastern window, the sun is only in the morning, I spray it a day or every other day out of the sun. All this time it dries out the tips (cut off), untwists new leaves, but with the same problems, the leaves feel like thick paper to the touch, elastic only after spraying. The underside of the sheet is unevenly colored.

Read: herbaceous plant of the pink, or carnation, family, native to the Mediterranean area.