Are there wingless ones, too? The aphids I usually see are wingless but I read that some can grow wings when it's time to look for other plants.
At any rate, make a neem oil spray. 4 tsp of neem oil, 2 tsp of dish soap (I try to use the clear, scent free kind) in a gallon sprayer of hot water. Give it a shake/mix and spray on your plants once a week.
I’ve never used peppermint oil on my plants, so I can’t speak to this.
If it’s convenient for you, I would consider reaching out to my favorite nursery and asking if they carry it or know where to find it. Chances are they will. I bought mine on Amazon and it worked really well for me. Your baby will be okay for a couple of days if it is a pest issue.
Here’s the link
I bought here on Amazon, I wanted to try out a small amount for a decent price. Premium Organic Neem Oil Virgin,... https://www.amazon.com/dp/B07G4JHDYG?ref=ppx_pop_mob_ap_share
Are those tiny black lines an insect? Might be thrips.
If not, check for root rot. If some roots are mushy, brown, and fall right off then it's root rot. If it's winter for you then root rot is highly probable.
If you do have root rot then you're either watering too often or the soil's drainage is too poor and anaerobic.
Root rot is caused by a fungus that thrives in wet soil, so you're going to need to get rid of all the dead roots, wash the plant thoroughly with water and repot it in some fresh potting mix.
I highly suggest a 50/50 coco coir and perlite mix with some organic fertilizer/compost.
Get some neem oil and make a 1:10 mix with distilled or rain water and spray it liberally all over the plant.
Neem oil is a natural and environmentally friendly insecticide and fungicide that's been used for centuries in Asia. It'll take care of both thrips or fungal root rot for you.
I always water and mist with distilled or rain water cause I don't trust tap water for my favorite plants.
R. Tetraspermas are vigorous plants so a little TLC will go a long way! Good luck :)