Is it safe for an 86 year old lady to take Ranitidine since 2002?

My Mum is 86 years old and has been taking 20mg Ranitidine Hydrochloride every night for 5 years as she has a hiatus hernia. She has been rushed into hospital twice now in 3 months with these symptoms: breathlessness, chest pain, limb pain, dizzyness, etc. Both occasions proved to be caused by 'heartburn/trapped wind'. She has insommnia, depression, suffers from lethargy and has had 3 severe kidney infections within the last 2 months. I would like to know if Rantitidine could be the cause as I have seen all the possible side-effects listed and they all seem to fit poor Mum! I asked her Doctor but all he said was " I don't know!" ...