Guppy has red spine

Hi! I'm new on this site and new in the hobby as well. I really need some help about my female guppy. She's been pregnant for almost a month now and gained boxy shape a week before. A few days ago, I saw a rip on her tail but I thought it was my sailfin molly who caused it since I saw the molly getting a bit agressive towards other fishes while eating. Since there wasn't any fray on her tail, I didn't pay it much attention. Two days ago, while I was moving her so that she could give birth, I noticed a red mark along her spine ending at her tail. Today I saw a similar line past her stomach as well. She's breathing fast as she did the last time she gave birth.
After seeing the red line, I did some research today and came across the name septicemia. I'm wondering if she has it. But then again, they're saying it's not curable and I don't want to lose her. Guess I fell in love with her since the moment I saw my first guppy fry swimming in the corner of tank.
I do a 30% water change every week. I'm not aware of the water parameters since I don't own a testing kit. Yes, I know it's a MUST to have the kit, but I've been really busy lately and I promise I will get one as soon as I can.
Can anyone please help me about her?

Picture of the fish in question?
Are any of the other fish acting strange or have this mark?

foxgirl158 said:

Picture of the fish in question?
Are any of the other fish acting strange or have this mark?

Click to expand...

Thanks for reply! Here's some picture of her...I put her in a glass to get the right angle...And no, I haven't seen any strange behaviour in any other fish in my tank. But I bought a pair of guppy a few days ago that I think are white tuxedo guppy. The male seem to have a reddish white tail...I thought it was just how its tail was. But now I'm not so sure. I'll put a picture of him too though it's a hazy one.

Okay, she's giving birth now!