my betta's gills turn brown around the edges when he flares? >.<

[inkrealm]

I've never seen him flare before ( he's still fairly new ) and he was sticking around the bottom a bit more than usual today so I put a black shirt around the outside of his tank between him and the window it's next to ( no direct sun ) and I guess he saw his reflection and started flaring. it scared me at first because I didn't see the reflection/flaring bit and he had some sudden brown marks that hadn't been there before D:
but after watching him for a bit I saw him flaring his gills and so I moved the shirt away so he wouldn't hurt himself ( because he hasn't got his normal coloring back from the cup yet and I'm scared his fins are still a bit fragile and really he himself as well )

my question is is he lacking or having too much of something in his environment though? he's gotten reddish brown on his ventral fins, and he has some speckles/ rings right behind his eyes in the shape of his gills of a similar shade... he's getting some red hues on his fins, mostly like said the ventrals REALLY noticeably, enough that I thought they were bleeding at first, and some hues of red on his anal fin, just from where the stomach goes into it, not further down. he's a blue VT, so I'm fairly sure he's just gaining his colors, but the extra brownish marks on the gills appeared so suddenly and left so suddenly, that I wanted to make sure. the inside of his gills were really vibrant, so is that when they puff up their colors get brighter? and maybe his were just showing for a split second? the marks were on the OUTSIDE of them. if you need anything lemme know though, thanks guys :D



HEATER INFO: ( it is heated don't worry >.<; )
the tank is a glass 5 gal w/ preset 50 watt heater supposed to keep it around 78 and a hood with a light that also warms the water some. the thermometer reads it lower than 78 but I the the thermo's just off because it's not digital not to mention it was less than five dollars, and everyone's said the heater should be fine.
but we get chills around here in the air sometimes like the kind that just gets into your bones no matter what you do so I wondered if his water was getting one of those and I thought I'd stick something between the glass and the window to help a tad >< he's swimming back around now, wanted to check on the colors though in case it's something he has too much or too little of...

TANK LEVELS:
his PH is a little down between 5-6 last I checked, but that shouldn't be too bad should it?
water hardness I'm not sure, seems I remember it being just a little below ideal,
and the Alk-Hardness ratio was off a little when I checked it, but that shouldn't be hazardous to him right?
it's not cycled yet but it's in process, and I did a 50 water change yesterday to get out some aquarium salt, so that shouldn't be an issue today.
he also hasn't eaten today, it's his digestion day because I accidentally forgot and fed him yesterday ><

[inkrealm]

edit: he's back to being kindof lazy, he keeps laying in a small space in one of the corners, and sometimes buries himself headfirst into some plants and stays there.... if I walk over he gets really active though; so is he just sleepy maybe? I try to keep the lights off but sometimes the tv is on late and it shines into the kitchen and I noticed the other night when I walked in to get some water without turning on the lights that he was swimming around..... just catching up on sleep maybe?