Supplementing

Hey ladies! I have a question that may be a dumb one. My son is 4 1/2 months and ebf. Recently my supply has dropped because I took some dayquil. I read that it was safe for breast feeding but I didn’t realize it would dry me out. I am currently trying to build my supply back up. I am going away for the weekend and I don’t have enough stored milk so I will have to provide formula. My question is, has anyone had to supplement for a couple days but was still able to breast feed? I will be pumping the whole time I am gone but I fear my baby wont go back to breast after formula. Sorry if the question is dumb. I am new to breast feeding. Thanks!