On Chemo for Lymphoma and infection keeps returning

My dad is 74 and very recently diagnosed with mantle cell lymphoma. He has had his first round of chemo but is now in and out of hospital with a fever which is always an infection. He’s been in hospital for a week over Christmas on antibiotics and then was sent home for only 12 hours before he’s got a temperature again and has been admitted to hospital again! 

is this common when having chemo treatment? Has anyone else been through this please I am so worried.