I still can't figure out how one login can give me -3 points. Very impressive. How many logins do you have? Must be a hassle keeping them straight, and you just burned three of them for one reply. Hardly seems sustainable.
1) I don't know whom you're addressing, but it's very unlikely someone used 3 different accounts to downvote you for something that isn't very political/controversial. For your reference, you can't downvote someone who replies to you, so it certainly wasn't me.
2) You can't "burn" downvotes. You have as many as you want, but can only downvote any eligible comment a single time. I can't remember what makes some comments ineligible, though.
3) You'll end up hating HN if you take downvotes personally. Downvoting is often a way to say "I disagree" without polluting the thread. Sometimes you hit a seam of (dis)approval, and there's no rhyme or reason to it. I hope a few downvotes won't stop you from participating, as there are a lot of brilliant people here who have interesting things to say.