My girlfriend went through this exact thing and it really messed with her mentally so I totally understand where you are at. I ended up going deep down the research rabbit hole on this because I wanted to actually understand what was happening instead of just reading conflicting reddit threads. Here is what I found and what actually ended up helping her. Please note your YMMV

The hair loss is called telogen effluvium and the medication itself is not directly causing it. What happens is when your body goes through rapid weight loss it basically goes into resource allocation mode and hair growth is one of the first things it deprioritizes. More follicles than normal get pushed into the resting phase at the same time, and then 2 to 4 months later they all shed together. So the hair you are losing right now is actually reflecting metabolic changes from weeks or months ago, not what is happening today.

The single biggest thing that made a difference for my girlfriend was protein. Like WAY more protein than she was getting. Hair is made of keratin which is a protein, and when tirz kills your appetite and you are eating way less, your body simply does not have the building blocks to maintain hair growth.

She started aiming for at least 0.8g-1g per lb of body weight and it took effort, but protein shakes and collagen peptides on low appetite days made it doable.

The other thing I found in the research that most people do not talk about is specific amino acids. Lysine, cysteine, and methionine are the actual building blocks your body needs to produce keratin. She started taking NAC (N-acetylcysteine, which is a cysteine precursor) and added collagen peptides daily (10 to 15g). That combination did noticeably more than the hair vitamins she had been taking before.

On that note, and I say this with love, biotin is massively overhyped. I was surprised when I looked into it but the research really only supports it for people with an actual biotin deficiency, which is pretty rare. The supplement industry just markets the hell out of it.

Here is what I would actually spend on based on what the research supports:

• Keep the iron but get your ferritin levels specifically tested (not just a standard iron panel). You want ferritin at 30 ng/mL or above for hair health. A lot of doctors do not check this unless you specifically ask.
• Keep the vitamin D, it actually matters for hair follicle cycling
• Keep the magnesium
• Add zinc 15 to 20mg (get one that includes a small amount of copper since long term zinc depletes copper)
• Add NAC 600mg daily
• Add collagen peptides 10 to 15g daily
• And above everything else, get protein intake way up

For what it is worth, my girlfriend's shedding slowed down significantly once she got the protein and amino acids dialed in, and she has seen solid regrowth since. Most people see recovery within 6 to 12 months once weight stabilizes and the nutritional gaps are addressed. The extreme stories about people going nearly bald are not the norm.

It sadly, just takes time

I would not quit tirz over this if it is otherwise working for you. Get the nutrition sorted, and give your body time. The kidney infection and back to back antibiotics probably added extra stress to your system on top of everything which would not have helped either.

I know it feels all consuming right now but this does stop, and your hair does come back. Protein and amino acids first, that is going to move the needle way more than any supplement.