Can my manager do this?

Yes, she can do this and yes, she can send you home tomorrow or even fire you if she wants to.

Are you that stupid you think it's a good idea to get into a stupid little pissing war with your boss?

So you're going to sashay in tomorrow even though your boss said not to. You and your 'tude will walk out of there saying, "Yeah, I showed her. I got fired, but I showed her."

You don't understand that bosses have heard it all before. If you're sick enough to stay home from work, it's never for one day. If you really are sick, they don't want you there because you'll spread it to everyone. Saying you're too sick today but tomorrow you'll be fine, dang it! is BS and they know it.

You've been told that your shift has been covered. She doesn't expect you to be well by tomorrow, and doesn't want to have to cover the shift at the last minute. She doesn't need your permission. Don't go in - she'll only send you home.

You don't have to say yes. She said no - and what she says is what counts. Of course she can do this. You are NOT on the schedule for tomorrow.

She can do this...sorry :(

It sounds like you are working in a place with variable hours. In that case, yes se can.

As an employer of many if you show up tomorrow I would fire. NO ONE and I mean NO one gets over a cold in one day and I do not wanting you making others sick.

Little **** ant do you really think you have a say in this? WRONG and leave off your anger I never come back to useless questions!

Yes, she can do this. She’s afraid that you’ll come back before you’re completely well and will get other people sick. You will just be wasting your time if you try to go in tomorrow.

Yes. Can be

your manager has more experience with replacing people for sicknesses, and is probably more aware of the time it will take you to recover
having a cold is not an overnite thing, generally it will last two weeks and your supervisor has had experience with this problem already

Yes she can. Managers make decisions based on the needs of the business and your performance, weather you think they're good or not is none of your business. You don't get to 'okay' what a manager decides (you're not her boss), she makes the decisions you have to live with them. You decided to be sick, she gave you an extra day. You don't have to go into work tomorrow, go to work when you your next scheduled to be there. She may only send you home if you show up, then there's too many people on the floor.

She's nervous that she's not going to to have someone there that will be able to take care of a lot of the things that she needs to have done that keeps the business going so she's making sure that she knows someone is going to be there and not calling in sick

A simple cold is no reason to skip work. You don't sound committed to your job. That was the opinion of your manager and that is the reason she is giving you two days off - another day in case your cold is so bad that you need another day and/or another day in which to think about whether she should fire you. What makes you think that she needs "your" permission to send you home for a day, to have someone else cover your shift? You work for her, not the other way around. You have NO SAY in the matter.

Either speak with her manager or register a complaint with H/R

Take his advice and see where it goes. Don't argue.

I suspect you have been taking off a lot, often with flimsy excuses, and they are tired of your BS. I also suspect you are close to getting canned.