Your cuckoo rooster is very handsome. Could your lavender rooster be having his molt? This could explain his comb shrinkage and acting backward, since molt is very hard on them. The first molt take place about 18 months, then yearly thereafter. Whether he is molting or not, after worming him, I would suggest that you put Avian Super Pack vitamins and Probios Dispersible Powder in his water 3 days a week, along with a 20% flock raiser feed to build him up.