Here is something I have just found that could help you decided what you need to do
Residents
If you plan to take up residence in Bulgaria and will be contributing to Bulgarian social security (called ‘NOI’) – e.g. if you will be working in Bulgaria – you and your family will be entitled to free or subsidised medical and dental treatment from the Bulgarian state system.
Once you have a residence permit you will pay contributions through the NOI to the Bulgarian state health system, currently around 15 lev per month. This entitles you to free treatment from a GP, free referrals to a specialist, and medicines at reduced prices or free.
SURVIVAL TIP
It’s recommended that you take out private health insurance while in Bulgaria, even if you’re a resident, as the standard of private health care tends to be much higher than that of the state system. You should also check your entitlements under the Bulgarian state health scheme and when such cover might become effective.
Residents who don’t contribute to social security (e.g. retirees) and aren’t covered by a reciprocal agreement should take out a private international health insurance policy.
SURVIVAL TIP
If you’re planning to take up residence in Bulgaria, you should ensure that you and your family have full health insurance during the interval between leaving your last country of residence and obtaining health insurance in Bulgaria.
One way to insure yourself for this interim period is to take out a holiday/travel insurance policy. If you already have private health insurance, it’s better to extend your present health insurance policy to provide international cover (which is usually possible) than to take out a new policy. This is particularly important if you have an existing health problem that won’t be covered by a new policy.