M:你感冒是不是又严重了? 你有点咳嗽，上午我都没见你咳嗽。 M:Have you taken a turn for the worse? You are coughing. I didn't see you coughing in the moring. F: 好像是有点。 F: Yes, I think I'm getting worse. M: 你吃感冒药了没有？ M: Have you taken any cold medication? F: 吃了，吃了点感冒药和消炎药。但是不可能这么快见效。吃不吃药，我感冒基本上都要一周才会好。 F: Yes I have. But it will take time to cure. Usually, the cold will last for 1 week no matter whether/if I take medicine or not. M: 我们家不是没有感冒药了吗？ M: I don't remember if we have any cold medicince at home, do we? F: 是没有了，我刚刚出去丢垃圾的时候在门口的药店买了点。 F: No, we don’t. But I bought some from the pharmacy near our building, when I was going to throw out the garbage just now. M: 总之你这两天注意点，别把儿子给传染了。 M: Pay attention to it anyway. Don't infect Derec. F: 我知道，不过他前几周感冒刚好，我估计他现在对感冒免疫。 F: I know, But I think he's immune to it right now, since he just recovered from a cold a few weeks ago. Nicely done. Take a close look at where I inserted whether or if into your writing.

To answer your question about “regardless” vs “no matter”, it seems to me that they are just used structurally differently, but mean the same thing. “Regardless” can stand alone at the end of a statement or stand before a “whether or not clause”. “No matter” needs to be followed by a clause (which usually starts with a question word - who/when/where/what). For example: The cold will last for a week no matter how much medicine I take. The cold will last for a week no matter what medicine I take. The cold will last for a week regardless of whether I take medicine or not. It doesn’t matter if I take medicine, the cold will last for a week regardless.

I’ll just rewrite your sentences here. The ones that I didn’t rewrite are fine. You are coughing and I didn’t see you coughing this morning. Yes, I have. But it will take time to take effect. Usually, the cold will last for at least a week (or if you want to say “about a week”) regardless if I take medicine or not. I don’t remember if we have any cold medicine at home, do we? But I bought some from the pharmacy near our building when I just threw the garbage out. Pay attention to it anyway. Don’t let Derec get infected. I know, but I think he’s immune to it right now since he just recovered from a cold weeks ago.