I Have A Urinary Infection. I Have Been Taking Hiprex

I have a urinary infection. I have been taking Hiprex but not working - I have a packet of amoxicillin and wanted to know can I start this now if I took a Hiprex 4 hours ago or do I need to wait? Ideally need to start ASAP as the infection is very painful. Always a sufferer and always get blood so have medication from doctor as back up for emergencies. Not taken Amoxocillian for 1.5 years now - know it works but just didn't want Hiprex to still be in my body in case it doesn't mix well!