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Most diseases that produce bumps on the fruit, called cankers, galls, or scabs, involve brownish discolorations of the bumps. This article shows the common examples: http://amarillo.tamu.edu/files/2010/11/CitrusCankerPathologyTrainingCHRP.pdf
If the bumps on your fruit aren't discolored, you might have a simple condition caused by nutrient imbalance or environmental stress. This article has information on tangerine growing: https://www.gardeningknowhow.com/edible/fruits/tangerine/mandarin-orange-tree-care.htm
Please consider making use if the resources at the County Extension Service. Take some samples to them; they will be able to tell you the cause and if anything needs to be done. This link will help you find the nearest office: https://www.gardeningknowhow.com/garden-how-to/info/what-is-extension-service.htm

Your tree is still young, so that is one reason why it might take longer to ripen fruit. Also, it probably doesn't have enough root development to ripen all those fruit, so you might want to remove 1/3 - 1/2 the fruit. Depending on the variety, citrus can take over a year to ripen, so patience is in order. Tangerine doesn't often need pruning, so I wouldn't worry about that at this point. These articles should be helpful: https://www.gardeningknowhow.com/edible/fruits/tangerine/tangerine-tree-care.htm
https://www.gardeningknowhow.com/edible/fruits/citrus/citrus-blooming-season.htm

Nematodes have been known to control thrip populations and these include the predaceous mite Euseius tularensis, spiders, lacewings, dustywings, and minute pirate bugs. There are chemical applications but thrips develop resistance quickly to them especially when the chemicals are used in large doses. Light doses of chemicals such as Spinosad, Kaolin, Formetanate Hydrochloride, Dimethoate, and Cyfluthrin have been shown to have some efficacy against thrips but you have to be careful that your chemical application doesn't kill the thrips natural enemies.

For more information on citrus thrips control, please visit the following link:
https://www.gardeningknowhow.com/edible/fruits/citrus/controlling-citrus-thrips.htm

If the tree was newly planted, it likely went into shock or something could be constricting the roots from taking up water. A fungus could also have affected your tree. You may be able to check if the tree is still alive by scraping the bark. If it's still green and the branches still pliable (able to bend without snapping off), then your tree is still alive. Treating it with neem oil and watering the tree when the soil becomes dry should help. Also, gently tamp down the soil when watering to collapse any possible air pockets. You may need to check the roots as well to see if there is a problem, such as rot. Here is more information on that: https://www.gardeningknowhow.com/plant-problems/disease/root-rot-in-garden-plants.htm

4 to 6 feet when cultivated in a container.

https://www.gardeningknowhow.com/edible/fruits/tangerine/tangerine-tree-care.htm

Care should be taken to only tent the structure.

You will have to wait and see as these chemicals can and will kill your plants both outdoors and indoors.