I’m really worried I’m going to be under the weather for my big day!

My wedding is less than a month away. Over the last two weeks I have been mega run down and constantly full of cold. I got rid of one cold then days later got another. I am feeling really rubbish (I can’t keep on track with my exercise and my skin has got really bad) and my hen do is next weekend! I’m really worried I’m going to be under the weather for my big day! Is there anything anyone can recommend? I’ve just started taking multivitamins xxx