Help! Fish not eating!

So I have had my crowntail male Betta for a few weeks now he has been transferred to a heated and filtered 10 gal and has been acting normal. A few days ago I went to feed him and he took it and just spit it out, he has been doing thing for 2-3 days now. I tried giving him flakes but he doesn't touch them. Any ideas?

Housing
What size is your tank? 10 gal
What temperature is your tank? Between 75-82 always
Does your tank have a filter? Yes
Does your tank have an air stone or other type of aeration? No
Is your tank heated? Yes
What tank mates does your betta fish live with? None

Food
What type of food do you feed your betta fish? Aqueon betta pellets
How often do you feed your betta fish? 2 pellets two times a day

Maintenance
How often do you perform a water change? Just got it so not regularly
What percentage of the water do you change when you perform a water change?
What type of additives do you add to the water when you perform a water change? Water conditioner

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Ammonia:
Nitrite:
Nitrate:
pH:
Hardness:
Alkalinity:

Symptoms and Treatment
How has your betta fish's appearance changed? No
How has your betta fish's behavior changed? Not really he is kind of mellow and I caught him laying inside a plant today but he has always been that way
When did you start noticing the symptoms? 2-3 days ago
Have you started treating your fish? If so, how? Not really i put him in a tiny cup for about 5 min and added flakes and pellets, he spit out the pellets and ignored the flakes
Does your fish have any history of being ill? No
How old is your fish (approximately)? I'm guessing pretty young but he is a lets art so hard to tell