Agony from sleeping on mattress of less than 7 years old

Do not buy a mattress here. I purchased a queen not more than 6 years ago through the owner. It was super comfortable at first but last year I started having back pain, realised the one side that I slept on was much softer than the unslept on side. I swapped it around but my lower back pain progressed so badly that I have could not sleep. I spent R1 000 at physio and more having massages. Physio could not find out what was wrong, he even sent me for a gout test! Luckily it was negative. Since purchasing another brand of new mattress 2 weeks ago, my back is 100%. Months of bad sleep. Dont buy here.