As a new parent I know how it feels if the baby cannot get the formula which suits their stomach. It can make the life of both the parent and baby in tears.
Now I am not a professional, nor a doctor, but a parent just like you. So please this is not medical advice.
If your baby is less than a year old, it is critical to find the perfect match of baby formula. If your little one is over 1, you can try many alternatives, such as pureed foods, or maybe even fresh goat milk. The reason I say goat milk, is my second child had issues with any kind of formula and milk, but once we put him on goat milk, he was doing great. Anyways, if over 1, relax and not worry that much.
My main concern is for the really little ones, my 8 month old is being breast fed, so we are lucky in a way. However, for my first child, I remember travelling when he was 6 months old, and we couldn't find the same formula, and it made the baby upset so much that we had to take him to the emergency. We ordered the goat milk from Europe after which things were normal. After that incident, I always had a minimum of 2 brands of formulas, one as a backup, and the other as a regular milk formula. And keeping more in stock is better, than running out or couldn't find your formula.
For our third baby, we tried every milk possible, but it just didn't solve our issue. So we ended up buying goat milk formula from the UK this time. I am not endorsing any brands or any country. however, please order formula from companies like https://myorganiccompany.store/ who can deliver within 2 to 3 days.
Now if affordability is an issue. First get advice from your doctor, and start giving your little one real food, such as oats with fresh fruits boiled and cooked, and pureed. Cooked Semolina with water is great as well. And the most simplest form is a ripe banana, mash and give it to them, or again puree it.
Now if you have a newborn or someone who is less than 4 months old. I suggest to have friends and family anywhere in the world and asking them to express ship the baby formula to you. You can even visit the hospital and ask for an emergency pre-made formula bottles if your baby is not drinking anything.
I hope now things are better for you, and that you were able to find the formula. I only wrote this article because I know how it feels being a new parent.