It simply isn't that time of year for Arty to moult (MOULTING: Cockatiels have their first moult at five or six months of age and thereafter, will usually moult once a year during the latter part of the summer. Their resistance is somewhat lower during this period and particular attention should be given to their diet. They should be protected from drafts, as they seem inclined to take colds easily during the moult. Occasionally, a sudden drastic change in temperature will cause cockatiels to moult out of season, but, unless the moult is continued, there is no cause for concern.)
You can find the complete article here.
HAMILTON & DISTRICT BUDGERIGAR & CAGE BIRD SOCIETY INC.
There is something else happening and I agree with the suggestion that its time for Arty to see a doctor.
I pray all goes well for both of you!
P.S.
I love you Artemis
Arty