让帮助睡觉楼主可以服用 50mg 的diphenhydramine (brand name is Benadryl). this is over the counter. take it with a some of milk or just water is fine.
I was going to suggest over the counter codeine cough syrup, (codeine + guaifenesin+pseudoephedrine). This is great at stopping cough and helps with sleep. However, Pseudoepehedrine is not recommended to be taken during pregnancy as it can affect fetal development, so do not use this.
Otherwise there really isn't much we can do with a post viral cough. You will just have to ride through it. Hopefully the benadryl will help you sleep.