Hi Sorin,
If your site tanked on 25th-26th April, then it is safe to presume that your site was indeed hit by the Penguin update. There was a smaller Panda update that happened on 18th April as well. If you have access to Google Analytics or rank trackers, you should be able to tell by looking at the dates whether it was Panda or Penguin.
Coming to the issue of your small website, I would agree with Sha. It would be most appropriate if you can disclose the affected URL on the forum for real helpful suggestions.
Penguin penalized everything that was on the 'over' side. It punished sites with over-optimization at each level. Be it links (internal and external both) or the covert keyword stuffing across web pages. Penguin's impact could be felt more extensively because it affected almost everything that an SEO would have done to boost site's rankings.
I guess, if you are really looking for non-generalized approach towards helping your cause, then website's url is much needed.
Best Regards,
Rajesh Dhawan