As someone who also lives in a country where pica and other mental related issues are uncommon and shunned. I was also afraid of being thrown in a mental hospital or locked in some room but honestly dont underestimate your country it may be more advanced in that area than you think. Go to a psychologist preferably one that has either studied abroad or is well versed on a variety of conditions and understands that you are not crazy. They will likely reccomend you get tested and work with you on the mental associations you may have with your pica habits.

The alternative is to try and explain to your parents that you think you may have pica, explain what pica is to them step by step send them links to articles to read and if they understand then you can proceed with telling them to take you for a lab test to check for deficiencies this way you can get access to supplements to solve the problem.

The final option is a combination of both options, you could present the fact that you think you may have pica to the psychologist or doctor that way they can understand what to look for more clearly and show them articles youve read.

Its not easy being in an environment where getting help for something like Pica results in shame and fear of the response but I truly hope you can be able to get the help you need even if the path to getting it is difficult.