suspension woes.. BANG when going over bumps

Hi all, got another problem (yay!)

Over the course of about an hour and a half (distance of about 55km) my car went from perfectly normal, to getting louder and harder jolts from my front right suspension when going over very minor bumps (not even potholes, just tiny grooves in the road) and by the time I was almost home it was very loud and stiff any time I went over even the slightest of bumps.
I had to take a speed bump in my street when I was getting home, took it at about 3km/h and it felt like I'd hit it at 70km/h.

Apart from the banging and the jolt I could feel, the steering was not off and there was no wobbling, rattling or anything of that kind. It's simply as if the shock from bumps is not being absorbed at all.

I have Tanabe coilovers up front if that changes anything for diagnosis.

When I mentioned the problem to my old man he told me that if it were the actual shock inside the coilovers then it would have gradually gone over some time, not quickly like it did.

Haven't had a chance to get under the car yet, and won't until at least next week. Does anyone have a rough idea of what the problem may be from what I've listed above? What could be worn/shot completely?

Most likely your shock absorber is damaged and needs to be fixed or replaced.