What do you do when your child does not want to go to school?

I take them to school anyway.

I don't really have any good suggestions for the other part. I am sure it's hard to feel different, although it's more common that most think. I have a good friend that has a DD that has problems with math and the sequencing in reading. She needs extra help and she goes to a tutor for help as well. Sometimes people just need a little extra help in certain areas to find a way to make sense of what they are working on. Of course, that doesn't help in the here and now.

The longer she waits, the more catch up she'll have. But if she is sick like that again, it's a good idea for you to go pick up her missed work so that she can work on it.

If my kids are too sick to go to school, they are too sick to play. They spend the whole day either on the couch with cartoons (if I'm feeling nice) or in their beds with books. There is no after school playing, there is nothing. I remind them of that when they come to me saying they're sick. Usually they change their tune and want to go to school (miraculous recovery). On the few times that they accept the boring, I know they really are sick.

If she doesn't want to go to the remedial classes I would ask if she's being picked on by other students. I know I was about that age when we moved and I had to go to a new school. All the new kids were downright rotten to me. That was also when all the bullying I endured started: 4th grade.

I have one school-aged child (8) & I generally hear her out for what she's feeling. This means I don't go right to the level of yes/no or "You have to go" when she says something like "I don't want to go to school" or "I hate Fridays, I'm not going." Rather than engaging on that level, I do a little listening.
Listening reflectively would mean noting "You really don't feel like going" or "You feel like staying at home," (etc.) which gives her some room to talk about what's prompting those feelings. When I engage on the yes/no level, we miss that process.
Making space for feelings is very helpful. I've never had to "make" her go, despite the fact that she's expressed real negativity!

I'd guess your DD was feeling dread. Having been out for a week might have her feeling a little intimidated/overwhelmed (makeup work.) Or if she's feeling stigmatized by the special ed, the week off likely was a relief from regular stress (shame.)

I used to be "sick" when I was picked on..:(