Parrotlet behavior changes and plucking.?

My two year old Parrotlet has started plucking his feathers throughout these past 4 weeks. I find this extremely odd because i play with him all the time! On top of this he wants nothing to do with my hands( when i pick him up he always bites or fly's away ) The only place he is kinda happy is on my shoulder (biting my shirt) or his cage. I have gotten him a larger cage, have been giving him vitamins, and taking him out more but if anything he has gotten worse. Have no idea what to do anymore that's why i'm here.
Answers

Quetzel

First, a health check by an avian veterinarian. Second, if there are no parasites or other health condition, slight misting a couple of times per week will encourage healthy grooming. Third, a healthier diet that includes fruits, vegetables, pellets, a few sunflower seeds every couple of days will help with dry skin. Fourth, use a room humidifier.

thebax2006

Birds need a bath once or more times a week. Have you been using a plant spray bottle to mist your birds weekly?