Doser Mishap: ALK at 6, Please Help!

[LeanneP]

My hose came off on my doser for my alkalinity and when I checked my levels a couple of days later (I was away) my alk was at 6.8. I dosed 25mls at 10 am this morning and by 5pm it was down to 6.4 so then over the next hour and a half I added another 125mls but it has now dropped to 6.0. My calcium is still being dosed as usual but it has gone from about 410 to just over 500 tonight. I am totally lost on what I should do and why the alk is not going up. Should I be adding more calcium to balance it? Have I totally screwed my tank? The tank is 90 gallons and my test kit is new so I know it is accurate. Any help would be much appreciated. Thanks. Leanne