its too risky for you to look for a job in Qatar on visit visa having no experience/or no employment certificates. applying for a medical license here in qatar will take time because the system here for processing papers for licensing is not organized yet. while waiting for you application you might work in a company or a job you dont want or if you are lucky, you'll be satisfied.
it is better if you apply in some agencies in the Philipines but it is much better if you will have more than 3 years work experience that will make your applications easier. and i think before you can apply for a medical license here in qatar i think you need atleast 3 years experience. but i guess you can visit here first if you want and you can always go back in the philippines. atleast you tried.