No worries Steve,
Thank you for clarifying the situation. Now if Zico is showing thinning of his hair but eating and not losing weight, then we do have to consider overgrooming being at the base of his hair loss. And if he is overgrooming, then we can certainly see vomiting due to the excessive volume of hair he will be ingesting when doing so.
Now to help you determine the trigger for his overgrooming, can you tell me:
Have you seen any changes to his skin (ie redness, ulcers, sores, crusts, scabs, etc)?
Are you seeing him groom more often?
Have you changed his diet in the past 4-6 weeks since signs started?
Any new environmental agents in use (ie new laundry soap, carpet powder,etc)?
Has anything changed in Zico''s life (ie new pets, new neighborhood cats, renovations, new people, changes to your schedule, new furniture, babies, etc)?
When did you last treat him for fleas? What did you use?