Fin Rot??

I have a male Halfmoon Twintail Betta named Craig. He is my first fish and I have only had him for three days. I have him in a 10 gallon tank with a heater, filter, and plenty of decorations and hiding spots. The first day I had him, his color was fine. His body is a beautiful dark blue, and his tail red. Yesterday I noticed that the coloration in his face is fading and turning white, and there is a small amount of darkness at the end of his tail. I'm a newbie so of course I automatically went to the internet. I have read that the discoloration is a result of stress and should be better within a few days, but I am also very paranoid that it is some sort of disease, especially with the darkness on his tail. Can anyone help me sort this out? I am already very attached to him and I don't want anything to happen to him. I want to try and be the best pet owner I can for him. I will post a picture of Craig for reference.

Doesn't look like fin rot, many bettas have a darker edge to their fins which often fades away as they mature. I'm a little more concerned with his head. You don't often hear about their heads changing color like that. I suspect it to be stress related, as many issues are.

Are there any other fish in the tank? Can you post a picture of the entire tank as well? Has he been eating?

He is a new fish in a brand new tank so it sounds to my the tank may not be cycle. I'd look into the Nitrogen cycle, tis very important for keeping fish healthy. If you are able, test the water for ammonia, nitrites and nitrates then post the results. What is the temp?

Fishy first aid would be water changes, so perhaps try changing a good 50% or so of his water.

There are no other fish in the tank. I did not get to cycle out the tank, as he was placed temporarily in a half gallon unheated, unfiltered tank, and I wanted to get him out as soon as possible. The tank stays at 78°F. I have not had a chance to buy at testing kit yet because I'm a little low on money at the moment. People on another forum say the tank should be fine because I have conditioned and cleaned the water properly. This morning I noticed he has light pinkish red streaks on his head now. I won't be home all day so I will get pictures of his head this evening and be sure to post. I will post a picture of his tank right now though. (I'm aware that plastic plants are a no no and am working on getting real plants ordered and into the tank as soon as I can)