Grunting/Straining & Red face while feeding

5 week old baby strains grunts and her face would turn really red. I thought at first she’s constipated but she poops quite often and still normal consistency. She also does this while shes laying in her bassinet, she makes alot of noises while grunting and straining it wakes me and my husband up all the time. I think its gas? What can I do to help her?